Onion Soup Recipe

1. Slice onions

Peel the yellow onions, cut in half pole-to-pole, then thinly slice into half-moons about 2–3 mm thick.

2. Sweat and caramelize

In a large heavy-bottomed pot over medium heat, melt 60 g unsalted butter with 15 ml neutral oil. Add the sliced onions, 8 g fine sea salt and 5 g granulated sugar. Stir to coat, then cook, stirring frequently, until onions are deeply golden brown and caramelized, about 40–55 minutes. Adjust heat between medium-low and medium so they soften and brown without burning. If the pan starts to stick excessively, add a tablespoon of water and continue stirring.

3. Season

Toward the end of caramelization, season with 1 tsp freshly ground black pepper. Scrape any browned fond from the bottom of the pot with a wooden spoon to incorporate flavor.

4. Deglaze

Increase heat to medium-high, pour in 120 ml dry white wine or dry sherry to deglaze the pot. Scrape any browned bits off the bottom and reduce the wine by about half, 2–3 minutes.

5. Add stock and simmer

Add 1.5 L veal stock, 3 sprigs fresh thyme, 1 bay leaf and 5 ml Worcestershire sauce. Bring to a gentle simmer, then reduce heat to low and simmer, uncovered, for 20–25 minutes to let flavors meld. Taste and adjust seasoning with coarse sea salt and additional pepper as needed. Remove thyme sprigs and bay leaf before serving.

6. Prepare bread slices

Preheat oven to 200°C (400°F). Lightly brush both sides of 6 bread slices with 15 ml olive oil and 15 g melted butter. Optionally rub both sides with the cut side of 1 garlic clove for a subtle garlic note. Arrange slices on a baking sheet.

7. Toast croutons

Toast the bread in the oven 6–8 minutes, flipping once, until golden and crisp. Remove and set aside.

8. Assemble cheese topping

Combine 180 g grated gruyere with 30 g grated parmesan (optional) in a bowl and mix. When ready to serve, place one toasted bread slice on top of each soup bowl (or in ovenproof bowls), then mound 30–40 g of the cheese mixture over each slice.

9. Melt cheese

Place bowls on a rimmed baking sheet and broil on high (or use a salamander) about 2–4 minutes, watching closely, until cheese is bubbling and lightly browned. Alternatively, finish under a 220°C (425°F) oven for 4–6 minutes.

10. Ladle hot soup into warmed bowls (leaving a small gap below the rim if you will place bread in the bowl). Place the prepared cheese-crusted crouton on top and garnish with 1 tbsp fresh thyme leaves. Finish with a light sprinkle of coarse sea salt and freshly ground black pepper to taste.

11. Serve immediately while the soup is hot and the cheese is melty. Estimated yield: 4 generous bowls.