French onion soup is one of the classic French bistro dishes, famously served to late night Parisian partygoers. But if you don't feel up to it at 2am or whenever you roll in, it makes a restorative lunch for a chilly weekend after a brisk walk in the snow.
If you want to make more of a meal of it follow it with a large plate of charcuterie (sliced saucisson, air dried ham and hunks of pate or rillettes) served with cornichons and crusty bread.
The critical thing is to cook the onions long enough, use some good stock and use a substantial densely textured bread, preferably a day or two old.
1 slightly stale sourdough baguette or other densely textured loaf
2-3 large mild onions (about 700g in total), peeled and finely sliced
2 tbsp olive oil
1 tsp sugar
1/2 tsp of dried thyme
A glass of dry white wine (about 150ml)
1.25 litres beef, chicken, turkey or vegetable stock ideally home made or at a pinch made with organic stock cubes
125g mature Gruyere cheese, rinded and coarsely grated
Salt, pepper and, if you need it, a few drops of vinegar
Preheat an oven to 180°C/350°F/Gas 4. Cut the bread into thickish slices (about 2 cm) and lay them on a baking tray. Bake for about 15-25 minutes until crisp and lightly browned, then set aside. Meanwhile peel and finely slice the onions. Heat the oil in a large ovenproof casserole, add the butter and tip in the onions. Stir so they’re thoroughly coated and leave on a low to moderate heat, stirring them occasionally until they go a rich, deep brown. This may take up to 40 minutes, depending how wet or dry your onions are. Add a little sugar once they start to brown and stir more regularly. You don’t want to burn them. Once they’re a good colour, stir in thyme and wine and let it bubble up and reduce by half then add the stock. Bring back to the boil and simmer for about 20-25 minutes. Check for seasoning adding salt and pepper to taste and a few drops of vinegar if you think it tastes too sweet.
Preheat a grill and lay the slices of baked bread over the surface of the casserole, pressing them down lightly into the soup. Scatter over the grated cheese and brown it under a grill for about 5-10 minutes until well browned and bubbling.
What to drink
Given this soup is supposed to be a restorative antidote to overindulgence you don't really need wine with it as well as in it. But a glass of Aligoté or other inexpensive dry white is traditional.