French Onion Recipe
Topped with sourdough bread and melted Gruyere cheese
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Ingredients
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Soup
Topping & Finishing
Method
Soup
- 1
Prepare onions
Peel and halve the onions lengthwise, then slice each half thinly (about 1/8 inch). Aim for even slices so they caramelize uniformly.
- 2
Caramelize onions
In a large heavy-bottomed pot or Dutch oven, heat 3 tablespoons butter and 1 tablespoon olive oil over medium heat until butter foams. Add all sliced onions, 1 teaspoon fine sea salt, and 1 teaspoon granulated sugar. Toss to coat, then spread the onions into an even layer. Cook, stirring every 4–6 minutes, adjusting heat as needed to maintain a steady gentle sizzle (reduce to medium-low if browning too fast). Continue for 35–45 minutes until onions are deeply golden brown and sweet. Scrape browned bits from the bottom occasionally; if they build up too much, deglaze in the next step.
- 3
Add flour and deglaze
Sprinkle 1 tablespoon flour over the caramelized onions and cook 1–2 minutes, stirring constantly to remove raw flour taste. Pour in 1 cup dry white wine (or additional beef stock if skipping wine) and scrape the bottom of the pot with a wooden spoon to lift fond. Simmer until wine reduces by half, about 3–4 minutes.
- 4
Simmer the soup
Add 6 cups low-sodium beef stock, 3 thyme sprigs, and 1 bay leaf. Bring to a gentle simmer, then reduce heat to low and simmer, partially covered, for 20–25 minutes to allow flavors to meld. Taste and season with freshly ground black pepper (~1 teaspoon) and additional salt if needed.
- 5
Topping & Broiling
- 6
Toast sourdough
Preheat the oven broiler and position a rack about 6 inches from the broiler element. Brush both sides of sourdough slices lightly with 1 tablespoon melted butter. Arrange on a baking sheet and broil 1–2 minutes per side until golden and crisp. Watch closely to avoid burning.
- 7
Assemble bowls
Ladle the hot soup into oven-safe bowls or crocks, filling to about 3/4 full to allow room for bread and cheese. Place one toasted sourdough slice on top of each bowl of soup.
- 8
Add cheese and broil
Top each bread slice with a generous amount of grated Gruyère (about 1/3 cup per bowl) and a sprinkle of the optional grated Parmesan. Place bowls on a baking sheet and broil until cheese is fully melted, bubbly, and lightly browned, about 2–4 minutes. Rotate as needed for even browning. Remove carefully with oven mitts.
- 9
Serve
Let bowls cool 2–3 minutes, then garnish with a small crack of black pepper or a thyme leaf if desired. Serve immediately—soup is best hot so the cheese is gooey and the bread softened by the broth.