Classic French Onion Soup
Onions cooked slowly in butter until deep brown and jammy, simmered with white wine, stock and thyme, then topped with crisp baguette toasts and Gruyère melted under the grill.
Ingredients
- 1.4 kg yellow onions 3 lb, about 6 large, halved and sliced 3–5 mm / ⅛–¼ in thick, root to tip
- 3 tbsp unsalted butter 45 g
- 1 tbsp olive oil 15 ml
- 1 ½ tsp fine sea salt divided, plus more to taste
- 120 ml dry white wine ½ cup
- 1 tbsp plain flour 8 g, optional
- 1.5 litres beef stock, or half beef and half chicken stock 6 cups
- 4 sprigs fresh thyme or ½ tsp dried
- 1 bay leaf
- ½ tsp freshly ground black pepper
- 1–2 tbsp dry sherry or brandy 15–30 ml, optional
- 1 tsp sherry vinegar or red wine vinegar if needed
- ½ baguette 120 g / 4 oz, sliced 1.5 cm / ½ in thick
- 1 tbsp olive oil 15 ml
- 200 g Gruyère 7 oz, coarsely grated, about 2 cups
- 25 g finely grated Parmesan ¼ cup, optional
Instructions
- Melt the butter with the oil in a large heavy pot over medium heat. Add the onions and 1 tsp salt, cover and cook 10–15 minutes until collapsed by about half.
- Uncover, reduce to medium-low and cook 45–60 minutes, stirring regularly and deglazing with 2–3 tbsp water whenever the bottom browns, until deep chestnut brown and jammy.
- Add the wine and simmer 2–3 minutes until nearly gone. Stir in the flour, if using, for 1 minute.
- Add the stock, thyme, bay, pepper and remaining salt. Simmer partly covered 25–30 minutes.
- Remove the herbs. Add the sherry or brandy and simmer 1 minute. Season, adding vinegar a few drops at a time if needed.
- Meanwhile, brush the bread with oil and bake at 180°C (350°F) for 10–12 minutes, turning once, until dry and crisp.
- Heat the grill (broiler) to high. Ladle the hot soup into oven-safe bowls on a baking sheet, float the toasts on top, and cover with Gruyère and Parmesan.
- Grill 10–15 cm (4–6 in) from the heat for 3–5 minutes until bubbling and browned in spots. Rest a few minutes before serving.
Notes
Oven method for the onions: after the covered stage, cook uncovered in a 200°C (400°F) oven for 1–1 ½ hours, stirring and scraping every 20 minutes.
No oven-safe bowls: melt the cheese on the toasts on a tray, then float them on the soup.
Vegetarian: rich vegetable stock with 1 tbsp soy sauce and a few dried mushrooms; use cheese made with vegetarian rennet.
Gluten-free: skip the flour and use gluten-free bread.
Storage: soup (without toasts and cheese) keeps 4 days in the fridge or 3 months frozen. Caramelised onions keep 5 days in the fridge.