Onion Soup Gratinée Recipe
caramelized onions, sherry broth, crouton, gruyère
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Ingredients
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Onion soup
Croutons & topping
Method
Onion soup
- 1
Prepare onions
Peel and thinly slice the yellow onions into uniform 1/8–1/4 inch slices. Aim for even thickness so they caramelize evenly.
- 2
Caramelize onions
Heat a large heavy-bottomed pot or Dutch oven over medium heat. Add the butter and 1 tablespoon olive oil. When butter foams, add sliced onions, sprinkle with salt and the 1/2 teaspoon sugar. Stir to coat. Cook, stirring every 3–5 minutes, adjusting heat to keep the onions gently sizzling but not burning. This process will take 35–45 minutes; continue until onions are deeply golden brown and richly caramelized. If onions start to stick, deglaze with a splash of stock or lower the heat. Toward the end, add the freshly ground pepper.
- 3
Deglaze
Increase heat to medium-high, add the dry sherry and the optional white wine, scraping up browned bits from the pan with a wooden spoon. Let the alcohol reduce by about half, roughly 2–3 minutes, so a concentrated flavor remains.
- 4
Simmer soup
Add beef stock, bay leaf, thyme sprigs, and Worcestershire sauce. Bring to a gentle simmer, reduce heat to low, and cook uncovered for 20 minutes to allow flavors to meld. Taste and adjust seasoning with additional salt and pepper if needed. Remove and discard bay leaf and thyme stems before serving.
Croutons & topping
- 5
Prepare croutons
While the soup simmers, preheat the oven to 200°C (400°F). Brush baguette slices lightly with 1 tablespoon olive oil on both sides and place on a baking sheet. Toast in the oven 6–8 minutes, turning once, until crisp and lightly golden. Rub the warm toasts with the cut side of the garlic clove for a subtle garlic flavor.
- 6
Assemble gratinée
Ladle the hot onion soup into ovenproof bowls or crocks, leaving about 1 cm of headspace. Top each bowl with 1–2 toasted baguette slices (depending on bowl size). Generously mound grated Gruyère over the crouton so it covers bread and slightly overlaps the rim. Sprinkle a little Parmesan on top if using.
- 7
Grill until golden
Place the filled bowls on a baking sheet and transfer to the oven set to broil/grill (high). Broil 3–6 minutes, watching carefully, until the cheese is bubbling and a deep golden brown. Alternatively, use a kitchen torch to evenly brown the cheese. Remove carefully (bowls will be very hot).
- 8
Serve
Let sit 1–2 minutes to set slightly, then serve the Onion Soup Gratinée hot, with an oven mitt or trivet to protect the table. Advise diners to sip carefully because cheese and broth retain heat.