Ingredients:

6 cups of thinly sliced yellow onions
4 tablespoons butter
1 tablespoon oil
1 teaspoon salt
1/4 teaspoon sugar (helps the onions to brown)
3 tablespoons flour
2 quarts boiling beef stock
1/2 cup dry white wine or dry white vermouth
Salt and pepper to taste
3 tablespoons cognac
Rounds of hard-toasted French bread
1 to 2 cups grated Swiss, Gruyere, or Parmesan cheese

Cooking Recipe:

Cook the onions slowly with the butter and oil in a heavy-bottomed, 4-quart covered saucepan for 15 minutes. Uncover, raise heat to moderate, and stir in the salt and sugar. Cook for 30 to 40 minutes stirring frequently, until the onions have turned an even, deep, golden brown. Sprinkle in the flour and stir for 3 minutes. Off heat, blend in the boiling beef stock. Add the wine, and season to taste. Simmer partially covered for 30 to 40 minutes or more, skimming occasionally. Correct seasoning. Set aside uncovered until ready to serve. Then reheat to the simmer (cook slowly) . Just before serving, stir in the cognac. Pour into a soup tureen or soup cups over the rounds of bread, and pass the cheese separately.