Ingredients
500 g (about 1 lb) onions, sliced, 50 g (about 1/2 cup) flour, 1500 ml (about 6 cups) beef broth.
Seasonings
Butter, as needed.
Instructions
1. Sauté the sliced onions in a large knob of butter until golden brown, then sprinkle some flour over them to help the edges caramelize, pour in beef broth (do not add salt), and simmer for 20 minutes.
2. Pour into a large soup bowl, sprinkle with some grated cheese, and serve with toasted thin bread slices.