- 2 tablespoons olive oil
- 3 tablespoons butter
- 4 yellow onions - peeled, halved and thinly sliced
- 2 tablespoons sherry wine vinegar
- 2 tablespoons sugar
- 1/4 cup dry sherry
- Salt and pepper, to taste
Melt oil and butter in a heavy soup pot over medium heat; add onions. Cook onions, stirring frequently, for 15 to 20 minutes, or until deep golden but not brown. Stir in vinegar, sugar and sherry. Bring to a simmer and cook, uncovered, for 2 to 3 minutes.