Making Vegetable Stocks and Soup Bases
A good vegetable stock turns a collection of simple ingredients into one of the most useful foundations in the kitchen. It can add depth to soups, stews, sauces, risottos, grains, beans and casseroles without determining the final flavour of the meal.
Stock can also make sensible use of small vegetables, herb stems and clean trimmings that might otherwise be wasted. However, a stockpot should not become a container for every kitchen scrap. Freshness, cleanliness and flavour still matter.
The best stock is made from ingredients that are good enough to eat, even when they are not attractive enough to serve on their own.
Understand Stock, Broth and Soup Base
These terms are often used interchangeably, but it is useful to distinguish their practical roles.
Vegetable Stock
A vegetable stock is a lightly seasoned liquid made by simmering vegetables, herbs and water. It is intended to become an ingredient in another dish.
Stock is usually kept relatively neutral and may contain little or no salt. This allows it to reduce during later cooking without becoming excessively salty.
Vegetable Broth
A broth may be seasoned more fully and can sometimes be served on its own. It may include additional vegetables, grains, pulses or other ingredients.
Soup Base
A soup base is a prepared mixture that reduces the amount of work needed later.
It might be:
A concentrated vegetable stock.
Cooked onion, carrot and celery.
Roasted tomato and pepper purée.
A blended courgette or pumpkin base.
A portion of cooked mixed vegetables.
A concentrated herb and vegetable mixture.
Soup bases are particularly useful for freezing in small portions.
Begin with Good Ingredients
Use sound, clean vegetables and herbs.
Suitable ingredients include:
Onions.
Carrots.
Celery.
Leeks.
Garlic.
Parsley stems.
Thyme.
Bay leaves.
Mushroom stalks.
Tomatoes.
Fennel.
Parsnips.
Celeriac.
Pea pods from edible peas, when fresh and clean.
Small quantities of other mild vegetables.
The balance matters more than the number of ingredients. Onion, carrot and celery provide a dependable foundation, but a useful stock can be made without all three.
Do not use mouldy, slimy, decaying or unpleasant-smelling vegetables. Long cooking does not make spoiled produce suitable for eating.
Use Trimmings Selectively
Clean trimmings can contribute excellent flavour.
Useful examples include:
Carrot ends and peelings.
Celery leaves and clean ends.
Leek greens.
Parsley stems.
Herb stems.
Onion ends and clean outer layers.
Mushroom stalks.
Fennel stalks and fronds.
Tomato ends.
Clean pieces trimmed from sound vegetables.
Wash vegetables before peeling or trimming them. Soil on a peeling will enter the stock if it has not been cleaned first.
Trimmings should be fresh. A bag of scraps that has become wet, slimy or forgotten in the refrigerator will not produce good stock.
What Not to Put in Vegetable Stock
Some plant parts are unsafe, while others produce unpleasant flavours or textures.
Do not use:
Tomato leaves or stems.
Potato leaves or stems.
Green or heavily sprouted potato peelings.
Rhubarb leaves.
Unidentified leaves or herbs.
Mouldy vegetables.
Rotten or fermented scraps.
Material contaminated by animals.
Tough plant parts that are not normally eaten.
Trimmings from produce treated with unsuitable chemicals.
Use brassicas such as cabbage, broccoli, cauliflower and Brussels sprouts sparingly. Long simmering can make them sulphurous and dominant.
Beetroot trimmings can colour the entire stock and add an earthy sweetness. Use them only when this suits the intended dish.
Large quantities of courgette, cucumber or lettuce can make stock watery without adding much flavour.
Very starchy vegetables can make the liquid cloudy and heavy. Potatoes are usually better added to the final soup than used as a main stock ingredient.
Build a Balanced Flavour
A versatile vegetable stock needs a balance of sweetness, savoury depth and aroma.
Sweetness
Carrots, onions, parsnips and some squashes add sweetness.
Too many sweet roots can make the stock taste more like a vegetable juice than a neutral cooking ingredient.
Savoury Depth
Onions, leeks, celery, mushrooms, garlic and roasted tomatoes provide savoury character.
Dried mushrooms can add considerable depth, but their flavour may dominate a delicate stock.
Freshness and Aroma
Parsley stems, thyme, bay, fennel fronds and other suitable herbs add aroma.
Strong herbs such as rosemary and sage should be used sparingly.
Bitterness
Burnt vegetables, excessive onion skin, mature brassicas and long-cooked herbs can introduce bitterness.
Taste the stock during cooking rather than assuming that a longer simmer will always improve it.
Basic Vegetable Stock
This adaptable stock provides a neutral foundation for many dishes.
Ingredients
2 onions
2 carrots
2 celery stalks
1 leek, optional
2 garlic cloves, optional
A small handful of parsley stems
2–3 sprigs of thyme
1 bay leaf
2.5 litres water
A few black peppercorns, optional
Prepare the Vegetables
Wash all the vegetables thoroughly.
Peel only where necessary. Cut them into rough, evenly sized pieces. Smaller pieces release flavour more quickly, but finely chopping everything creates unnecessary work and can make straining difficult.
Cook the Stock
Place the vegetables, herbs and water in a large pan.
Bring the water towards a boil, then reduce the heat and simmer gently. Vigorous boiling can break the vegetables apart and produce a cloudy stock.
Simmer for approximately 45–60 minutes.
Taste after about 30 minutes. Remove any herb that is becoming too dominant.
Strain the Stock
Pour the stock through a fine sieve into a clean container.
Pressing the vegetables firmly will increase yield but may make the stock cloudy. For a clearer liquid, allow it to drain naturally.
The cooked vegetables will have given much of their flavour to the liquid. They can be composted once cool unless another suitable use remains.
Season Later
Leave the stock unsalted or only lightly salted.
The stock may be reduced or combined with salty ingredients in the final dish. Seasoning at that stage gives better control.
Make Roasted Vegetable Stock
Roasting creates a darker, richer stock.
Use onions, carrots, celery, leeks, mushrooms, tomatoes or other suitable vegetables. Cut them into pieces, add a small amount of oil and spread them across a shallow tray.
Roast until the edges are well browned but not burnt.
Transfer the vegetables to a stockpot. Add water and herbs, then simmer gently.
Deglaze the roasting tray with a little hot water and add the browned juices to the pan.
Roasted stock works particularly well in:
Dark soups.
Lentil dishes.
Mushroom dishes.
Bean stews.
Gravies.
Rich vegetable sauces.
A pale stock is usually better for delicate soups and light-coloured sauces.
Save Trimmings in the Freezer
A freezer container can collect suitable stock ingredients until there is enough for a batch.
Useful additions include:
Onion ends.
Carrot peelings.
Celery leaves.
Leek greens.
Parsley stems.
Mushroom stalks.
Fennel trimmings.
Small tomato pieces.
Wash all produce before preparing it. Freeze the trimmings while they are still fresh rather than after they have begun to deteriorate.
Label the container clearly and keep an eye on its balance. A bag containing mostly carrot peelings or leek tops will produce a one-dimensional stock.
Avoid repeatedly opening the freezer to add warm scraps. Cool any cooked ingredients before freezing and keep raw additions clean.
When the container is full, use the frozen vegetables directly in the stockpot.
Make a Concentrated Stock
Concentrated stock saves freezer space.
Make and strain a normal vegetable stock, then return the liquid to a clean pan. Simmer it uncovered until its volume has reduced and the flavour has become noticeably stronger.
Do not add much salt before reducing.
Cool the concentrate promptly and freeze it in small measured portions. Label the container so that it is not mistaken for ready-to-use stock.
When cooking, dilute the concentrate with water according to taste.
A very concentrated reduction can be frozen in small trays and added directly to sauces, stews and grains.
Make an Onion, Carrot and Celery Soup Base
Preparing the first stage of a soup in advance can save more time than making stock alone.
Ingredients
2 parts onion
1 part carrot
1 part celery
A small amount of cooking oil
The proportions can be adjusted to suit the available harvest and the dishes normally cooked.
Method
Chop the vegetables evenly.
Cook them gently in a broad pan with a small amount of oil. Stir regularly until the onions are translucent and the vegetables have softened.
Continue cooking for a deeper flavour, but do not burn the edges.
Cool the mixture promptly and divide it into portions suitable for one soup, stew or sauce.
Freeze and label the portions.
This base can later be cooked with tomatoes, beans, lentils, potatoes, grains, courgettes, leafy vegetables or almost any other seasonal crop.
Make a Roasted Tomato and Pepper Base
A tomato and pepper base is useful for soups, sauces and stews.
Roast ripe tomatoes, sweet peppers, onion and garlic until softened and lightly coloured. Remove pepper skins if a smoother result is wanted.
Blend the vegetables or leave them textured.
Return the mixture to a pan and reduce it if it is very watery. Keep the seasoning simple so that each frozen portion remains adaptable.
Cool promptly and freeze in measured portions.
Use it as the beginning of:
Tomato soup.
Pepper soup.
Pasta sauce.
Bean stew.
Curry.
Shakshuka-style dishes.
Braised vegetables.
Make a Courgette Soup Base
Courgettes can provide body for soup without imposing a strong flavour.
Cook chopped courgette with onion and a small amount of garlic. Add only enough liquid to prevent sticking because courgettes release considerable water.
When tender, blend the mixture.
Freeze it without dairy and add cream, yoghurt, cheese or other finishing ingredients after reheating.
This base can later be flavoured with:
Basil.
Dill.
Mint.
Parsley.
Curry spices.
Roasted garlic.
Tomato.
Beans.
Make a Pumpkin or Winter Squash Base
Roast or steam sound pumpkin or winter squash until tender.
Scoop the flesh away from the skin and blend it. Freeze the purée plain or combine it with cooked onion.
Plain squash purée can become:
Soup.
Curry.
Sauce.
Bread.
Cake.
Pie filling.
A thickener for stews.
Avoid adding dairy before freezing unless the complete recipe is known to freeze well.
Clearly distinguish plain squash purée from a fully seasoned soup when labelling.
Make a Beetroot Soup Base
Cook beetroot with onion and, if wanted, carrot or apple. Blend it with enough stock to create a thick base.
Freeze it in practical portions.
After thawing, it can be turned into a smooth soup or extended with cabbage, potatoes, beans and other vegetables.
Beetroot’s colour will stain pale freezer containers and utensils, although this does not usually affect their function.
Use Herb Stems
Tender herb stems often contain as much flavour as the leaves.
Suitable stock additions include:
Parsley stems.
Coriander stems.
Dill stems.
Thyme stems.
Small amounts of rosemary stem.
Fennel stalks and fronds.
Tie loose herbs into a bundle or place them in a reusable infuser if easy removal is important.
Avoid adding large quantities of flowering or seeding herbs unless their stronger flavour is wanted.
Woody stems should be strained out completely before the stock is used.
Use Mushroom Trimmings
Mushroom stalks and clean trimmings add savoury depth.
Use cultivated edible mushrooms or wild mushrooms identified with complete certainty by a suitably knowledgeable person.
Do not use unknown fungi.
Fresh mushroom trimmings can be frozen with other stock ingredients. Dried mushrooms can also be added, but a small quantity may be sufficient.
Dark mushroom gills can change the colour of the stock. This is not necessarily a problem in dark soups and sauces.
Keep Stock Neutral and Flexible
It is tempting to add every herb and spice available, but a neutral stock has more uses.
Avoid strong seasoning if the stock might later be used in several different cuisines.
A basic stock can become:
A herbed soup.
A spiced curry.
A tomato sauce.
A bean stew.
A risotto.
A gravy.
A grain cooking liquid.
Strong flavours can always be added later. They are difficult to remove once they have been concentrated into the stock.
Cool Stock Promptly
A large pot of hot stock cools slowly. Leaving it at room temperature for an extended period allows microorganisms to multiply.
After straining:
Divide the stock into smaller quantities.
Transfer it to shallow heat-safe containers.
Use an ice-water bath if faster cooling is needed.
Stir the stock with a clean utensil to release heat.
Refrigerate or freeze it promptly.
Do not place one very large, tightly covered, steaming pot into an overcrowded refrigerator and assume its centre will cool quickly.
Follow the food-safety guidance issued for the country in which the food is being prepared.
Label refrigerated stock with the preparation date and use it within the recommended period. Freeze it when it will not be used promptly.
Freeze Stock in Useful Portions
Freeze stock according to the way it will be used.
Useful portion sizes include:
Small cubes for sauces.
One-cup portions for grains and risotto.
Half-litre portions for soup.
Concentrated portions intended for dilution.
Flat freezer bags for efficient storage.
Leave expansion space in rigid containers.
Freeze bags flat on a tray before storing them upright. Ensure the bags are securely sealed and protected from punctures.
Include the following information on the label:
Type of stock.
Date.
Quantity.
Whether it is concentrated.
Any dominant ingredient.
Whether salt was added.
Reheat Stock Thoroughly
Thaw frozen stock in the refrigerator or reheat it directly from frozen in a suitable pan.
Bring it to a thorough simmer or boil as appropriate for the final recipe.
Only reheat the quantity needed. Repeated cooling and reheating reduce quality and increase opportunities for unsafe handling.
Discard stock that has been left at an unsafe temperature, has an unusual smell, shows unexpected fermentation or has been stored longer than recommended.
Do not taste questionable stock to decide whether it is safe.
Do Not Water-Bath Can Vegetable Stock
Vegetable stock is a low-acid food. A boiling-water canner does not reach the temperature required to preserve it safely.
Shelf-stable vegetable stock requires a scientifically tested pressure-canning recipe, suitable pressure-canning equipment and precise adherence to:
Ingredient restrictions.
Preparation method.
Jar size.
Headspace.
Processing time.
Pressure.
Altitude adjustments.
An ordinary pressure cooker is not automatically a pressure canner.
Do not create a canning process for a thick soup base, purée or homemade mixed stock. Density and ingredient composition affect heat penetration.
If an exact tested method is unavailable, freeze the stock instead.
Keep a Simple Stock Routine
A manageable routine prevents trimmings from becoming another form of waste.
Wash produce before trimming it.
Save only clean, useful pieces.
Freeze them while fresh.
Keep the mixture balanced.
Make stock when the container is full.
Strain and cool it promptly.
Freeze it in useful portions.
Compost the spent vegetables.
Do not keep scraps merely because they could theoretically be used. If they will overpower the stock or remain forgotten in the freezer, composting them is the better choice.
Turn Small Harvests into Useful Ingredients
A handful of carrots, a few small onions, celery leaves and herb stems may not appear to make a meal. Together, they can create the foundation for several meals.
Record larger harvests in Your Growing Companion and note which crops regularly produce small or surplus vegetables suitable for soup bases.
The purpose is not to account for every peeling. It is to recognise patterns. If tomatoes, courgettes or squash regularly arrive in large quantities, preparing a few dependable frozen bases may be more useful than searching for a different finished recipe every time.
More than a Use for Scraps
Good stock is made deliberately.
Clean trimmings can reduce waste, but fresh vegetables provide the structure and balance. Choose ingredients for their flavour, avoid unsafe plant parts and keep strong vegetables under control.
Cook the stock gently, strain it before bitterness develops, cool it quickly and freeze it in quantities that match the way the kitchen actually works.
A supply of well-labelled stock and soup bases turns the garden harvest into convenient ingredients that remain useful long after the original vegetables were picked.
