2 tablespoons rendered duck or goose fat
2 large onions, peeled and thinly sliced
1 large head garlic, peeled and chopped
2 tablespoons flour
6 cups chicken stock
2 egg yolks
1 tablespoon vinegar
salt and pepper to taste
Garnish:
several thin slices dried bread
fresh chives, chopped
gruyere cheese, grated

1. Heat the goose or duck fat in a large saucepan. Add the onions and cook over low heat until golden brown. Add the chopped garlic and cook for 2-3 minutes. Sprinkle the flour over the garlic, stirring with a wooden spoon. Add the chicken stock and season with salt and pepper to taste. Bring to a simmer and cook for 15-20 minutes at low heat.
2. Remove the soup from the heat. Beat the egg yolks with the vinegar. Temper this liaison with some of the hot soup and pour the mixture back into the pot, stirring until well mixed. Place the dried bread slices in the bottom of the serving bowls. Adjust the seasoning on the soup and ladle the soup over the dried bread.
3. Serve with grated cheese and garnish with chives; serve immediately.