Ingredients include:
Three tablespoons of butter or margarine.
Ten onions, sliced thinly.
50 grams of unflavored flour.
The tomato purée should be 1 tablespoon.
1 liter chicken or vegetable stock is 1 liter of chicken or vegetable stock.
100 gr grated Gruyère cheese, 100g
Four slices of toasted French bread.
Preparing.
Melt the butter in a large saucepan over low heat, and then cook the onions for 30 minutes until softened, stirring constantly.
Add the flour, tomato purée, and stock. Mix thoroughly. Cook for an additional 30 minutes. Add salt and black pepper to taste.
The grated cheese should be tossed over the toasted French bread slices and grilled until golden and bubbly.
Serve the soup immediately, with the cheese-topped toast floating on top, with the toast floating on top.