By Simran Makkar
September 10, 2026
Some soups you cook. This one, you wait for. Onions, sugar, salt, and a splash of wine are all it takes, but the real ingredient is time in this recipe. Leave the onions to slowly caramelise until they turn deep, jammy brown, transforming into a broth so rich and piquant that it barely needs anything else. At the end, you'll get a soup that can turn any rough day completely around.
– 1 tablespoon olive oil – 1 teaspoon salt – 3 tablespoons butter – 4 large onions, thinly sliced – 2 cloves garlic, minced – 1 teaspoon sugar – ½ cup dry white wine – 6 cups vegetable stock – 1 teaspoon black pepper, freshly ground – 1 bay leaf – 2 sprigs fresh thyme – 1 ½ cups Gruyère cheese, grated – 4 thick slices of baguette
In a large, heavy-bottomed pot, melt the butter with the olive oil over medium heat.
Add the onions, sugar and salt. Cook, stirring occasionally, until the onions soften.
Lower the heat and continue cooking the onions, stirring every few minutes, until they turn deep golden brown and caramelised. This can take about 35 minutes, so be patient.
Add the garlic and cook for another minute until fragrant.
Pour in the white wine, scraping up any browned bits from the bottom of the pot, and let it simmer until slightly reduced.
Add the bay leaf, stock, black pepper and thyme. Bring to a boil, then reduce heat and simmer for roughly 30 minutes.
Remove the bay leaf and thyme sprigs. Taste and adjust seasoning if required.
Meanwhile, toast the bread slices until golden and crisp.
Ladle the soup into oven-safe bowls, top each with a slice of toasted bread, and generously cover with Gruyère cheese.
Broil until the cheese melts, bubbles, and turns golden. Serve hot.