Slow-Caramelised French Onion Soup with a Comté Crown

⏱ 105 min · Serves 4

Six onions, an hour of patient stirring and a splash of dry sherry make a broth so deep and sweet it tastes like it simmered for days. Crowned with a raft of sourdough under a bubbling, blistered lid of nutty Comté, this is the bistro classic done properly — and worth every minute.

Per serving: 642 kcal · 29.0g protein · 52.0g carbs · 34.0g fat

Ingredients

• 1.2kg brown onions (about 6 large), halved and finely sliced
• 50g unsalted butter
• 1 tbsp olive oil
• 1 tsp caster sugar
• 1 tsp fine sea salt
• 3 garlic cloves, thinly sliced
• 2 tbsp plain flour
• 100ml dry sherry or dry white wine
• 1.4 litres good beef stock (or rich brown chicken stock)
• 3 sprigs thyme
• 1 bay leaf
• 1 tsp sherry vinegar
• Freshly ground black pepper
• 8 slices sourdough baguette, about 1.5cm thick
• 1 garlic clove, halved, for rubbing
• 200g Comté, coarsely grated
• 20g Gruyère or Parmesan, finely grated (optional, for extra browning)

Method

1. Melt the butter with the oil in a wide, heavy casserole over a medium-low heat. Add the onions, sugar and salt, stir to coat, then cover and sweat for 15 minutes until collapsed and juicy.
2. Uncover, raise the heat slightly and cook for 45-55 minutes, stirring every few minutes and scraping the base, until the onions are deep mahogany, jammy and reduced to a fraction of their volume. Don't rush this — colour is flavour.
3. Add the sliced garlic and cook for 1 minute, then stir in the flour and cook for a further 2 minutes to lose the raw taste.
4. Pour in the sherry and bubble hard, scraping up every sticky bit from the base of the pan, until almost evaporated.
5. Add the stock, thyme and bay. Bring to a gentle simmer and cook, uncovered, for 30 minutes. Fish out the herbs, then season with the sherry vinegar, plenty of black pepper and more salt if needed.
6. Meanwhile, heat the oven to 200C/180C fan. Lay the sourdough slices on a tray and bake for 8-10 minutes until dry and crisp, then rub one side of each with the cut garlic clove.
7. Heat the grill to high. Ladle the soup into four ovenproof bowls, set on a sturdy baking tray. Float two toasts on each, then pile the Comté and Gruyère generously over the bread and right to the rim of the bowls.
8. Grill 10-12cm from the element for 4-6 minutes until the cheese is molten, bubbling and blistered dark in patches. Rest for 2 minutes — the soup is lava-hot — then serve at once.