- 2 tablespoons [30 g] butter, more if needed
- 3 medium-size Spanish onions, sliced
- 1/4 cup [60 mL] dry white wine
- 2 tablespoons [17.5 g] flour
- 6 cups [1.5 L] warm beef stock
- 1 bay leaf
- Salt and pepper, to taste
- 1 drop Tabasco sauce
- 1 1/2 cups [340 g] grated Gruyere cheese
- 4 slices toasted French bread
- Melt butter into a medium saucepan.
- Add and cook onion slices over very low heat for 20 minutes, stirring occasionally, adding a little more butte if needed.
- Increase heat to high and pour dry white wine into saucepan; leave to reduce by 2/3rds.
- Reduce heat to medium and sprinkle the flour over the onions.
- Stirring, slowly pour in warm beef stock.
- Add bay leaf; salt and pepper.
- Bring to a boil then leave soup to simmer over low heat, uncovered, for 30 minutes.
- Stir in Tabasco sauce then correct seasoning.
- Remove bay leaf.
- Preheat oven broiler.
- Spoon 1 tablespoon [15 g] grated Gruyere cheese into each of 4 oven-proof onion soup bowl.
- Evenly pour soup into bowls.
- Cover the soup with a slice of toasted French bread.
- Evenly sprinkle bread slices with remaining grated Gruyere cheese.
- Transfer bowls over middle rack of oven.
- Broil soups for 15 to 20 minutes, before serving.