Deeply caramelised onions are the heart of this French classic. Give them time: a dark golden colour brings sweetness and depth without added sugar.
Serves 4 | Preparation: 15 minutes | Cooking: 85 minutes | Total: 100 minutes
Ingredients
1 kg onions, peeled and thinly sliced
40 g butter
15 ml olive oil
2 garlic cloves, finely chopped
15 g plain flour
150 ml dry white wine
1.2 litres good beef stock
2 thyme sprigs
1 bay leaf
4 slices baguette (about 120 g)
100 g Gruyère, grated
Salt and black pepper
Method
Melt the butter with the oil in a heavy saucepan. Add the onions and a small pinch of salt. Cook over a low-to-medium heat for 45–60 minutes, stirring often, until very soft and deep golden brown. Add a splash of water if they catch; do not let them burn.
Stir in garlic for 1 minute, then flour for 1 minute. Add wine and scrape up the browned juices. Simmer for 3 minutes.
Add stock, thyme and bay. Simmer gently for 25 minutes. Remove herbs and season to taste.
Toast the bread. Heat the grill. Ladle soup into four grill-safe bowls on a baking tray, add toast and cheese, and grill for 2–4 minutes until bubbling. If your bowls are not grill-safe, grill the cheese-topped toasts separately and float them on the soup. Serve carefully: bowls will be very hot.
Variations and substitutions
For a vegetarian version use a rich vegetable or mushroom stock and vegetarian hard cheese. Replace wine with 150 ml additional stock plus 10 ml wine vinegar, adjusting to taste. Use gluten-free flour and bread if needed; check stock ingredients.
Homegrown and seasonal produce
Sound stored onions make this a useful winter recipe. Use yellow or brown onions for reliable caramelisation; discard soft, mouldy or rotten bulbs. Homegrown thyme can be used fresh, or replace with ½ tsp dried thyme.
Storage and freezing
Store the soup base separately from the bread and cheese topping. Cool in shallow containers and refrigerate within 2 hours at 5°C or below; eat within 48 hours. Freeze the base for up to 3 months. Defrost in the fridge and use within 24 hours. Reheat once until piping hot, then add freshly prepared cheese toast.
Explore our growing guides and From Garden to Kitchen guide. Plan your next harvest with Your Growing Companion.
Stock photograph for serving inspiration.
