Description
Slow heating breaks the sugars inside onion cells into smaller pieces that recombine into brown molecules. Those molecules add deep sweetness and roasted flavor while the onions soften and release their juices into the broth.
Cultural Background
Onion soups appeared in France by medieval times when cooks simmered sliced onions in water or broth. The version with cheese melted on bread dates to the mid nineteenth century. At that time restaurants around the Les Halles food market in Paris served it to workers and late night visitors. One documented story tells how the gratin topping of grated cheese and toasted bread turned a simple peasant broth into a dish served in elegant cafés. The key change happens when onions cook for forty five to sixty minutes at low heat. Heat first drives water out of the onion cells. Once the water is gone the temperature rises enough for the natural sugars in the onions to break apart. The broken sugar pieces then join into new larger molecules that taste sweet and smell toasted. This process is called caramelization. The craft that decides success is steady low heat with occasional stirring so the onions turn deep brown without blackening. A surprising true fact is that the modern gratin version spread from market workers to the rest of France only after the 1850s.
Recipe Info
PREP TIME: 20 minutes
COOK TIME: 1 hour 40 minutes
TOTAL TIME: 2 hours
SERVINGS: 6
DIFFICULTY: Medium
Ingredients
- 3 pounds yellow onions, halved, peeled, and sliced 1/4 inch thick
- 4 tablespoons unsalted butter
- 1 1/2 teaspoons kosher salt, divided
- 1/2 cup dry white wine
- 8 cups unsalted beef stock
- 1 bay leaf
- 1/2 teaspoon ground black pepper
- 2 tablespoons brandy
- 6 slices French bread, 1 inch thick
- 1 1/2 tablespoons olive oil
- 1 1/2 cups grated Gruyère cheese
Instructions
- Adult: Halve and peel the onions then slice them 1/4 inch thick.
- Adult: Melt the butter in a large heavy pot over medium heat.
- Add the sliced onions and 1 teaspoon of the salt.
- Cook the onions, stirring every few minutes, until they soften and turn deep golden brown, about 45 to 60 minutes.
- Adult: Raise the heat to medium high and pour in the wine.
- Scrape the bottom of the pot to loosen any browned bits and cook until the wine mostly evaporates, about 3 minutes.
- Adult: Add the beef stock, bay leaf, remaining salt, and pepper.
- Bring the soup to a simmer and cook for 30 minutes.
- Adult: Stir in the brandy and taste for salt.
- Adult: Heat the oven broiler.
- Brush the bread slices with olive oil and toast them under the broiler until golden.
- Ladle the soup into oven safe bowls.
- Adult: Place a toast on each bowl and top with grated cheese.
- Adult: Broil the bowls until the cheese melts and browns in spots, about 2 minutes.
Tips
- Onions that stay pale mean the heat was too low or the time too short; keep cooking until they reach a rich brown color.
- Use chicken stock if beef stock is unavailable.
- Cook the onions even slower next time for deeper flavor.
Nutrition
Calories: 380
Protein: 15 g
Carbs: 35 g
Fat: 20 g