Ingredients
Main Ingredients
- 5 large yellow onions
- 4 large shallots
- 3–4 tablespoons olive oil
- 3 tablespoons salted butter
- 1 tablespoon all-purpose flour
- 3 quarts beef stock
- ½ tablespoon beef base (low sodium preferred)
- 2 sprigs fresh thyme
- 2 fresh bay leaves
- Salt and pepper to taste
For Serving
- 6 thick slices rustic bread
- Salted butter, room temperature
- 2 cups grated Gruyère cheese
- Thinly sliced fresh chives (optional)
Instructions
- Prepare the onions and shallots: Peel and halve the onions and shallots, then slice them about ⅛-inch thick for even caramelization.
- Start cooking the onions: Heat the olive oil in a large Dutch oven over medium heat. Add the sliced onions, shallots, and a few pinches of salt. Cook until they become translucent, stirring occasionally.
- Caramelize the onions: Add the salted butter and reduce the heat to low. Cook the onions slowly, stirring occasionally, until deeply caramelized, about 45 minutes to 1 hour. If they begin to stick, add a splash of water to prevent burning.
- Add flour: Sprinkle the all-purpose flour over the caramelized onions and stir well for about 1 minute to cook off the raw flour taste.
- Make the soup base: Pour in the beef stock and add the beef base, fresh thyme sprigs, and bay leaves. Stir to combine thoroughly.
- Simmer the soup: Increase the heat to medium and bring the soup to a gentle simmer. Let it simmer uncovered for 20–30 minutes to develop flavors. Remove the thyme sprigs and bay leaves, then season with salt and pepper to taste.
- Prepare the bread: Preheat your oven’s broiler and position the rack at the top. Butter both sides of the rustic bread slices. Toast them in a skillet or on a griddle until golden brown on each side.
- Assemble the soup bowls: Place oven-safe soup bowls on a rimmed baking sheet. Fill each bowl slightly over halfway with the hot soup. Top each bowl with a slice of toasted bread and a generous handful of grated Gruyère cheese.
- Broil the cheese: Place the baking sheet under the broiler and broil until the Gruyère cheese melts and is browned in spots, watching closely to prevent burning.
- Garnish and serve: Remove from the oven, garnish with thinly sliced fresh chives if desired, and serve immediately for best flavor and texture.
Notes
- Using a mandoline slicer helps achieve uniform thin slices of onions and shallots, speeding cooking and improving texture.
- You can prepare the soup base ahead of time; however, add the toasted bread and cheese just before serving to maintain texture and crispness.
- The amount of bread may vary depending on the size and shape of your soup bowls.
- Prep Time: 10 minutes
- Cook Time: 1 hour 30 minutes
- Category: Soup
- Method: Stovetop
- Cuisine: French
