- 1/3 cup sugar
- 1 tablespoon water
- 4 tablespoons unsalted butter
- 1/2 cup plus 2 tablespoons balsamic vinegar
- 1 1/2 pounds cipollini onions
- Strips of zest from 1 lemon
- 4 fresh bay leaves
- 3 cups chicken stock or low-sodium broth
- Salt and freshly ground pepper
In a large saucepan, dissolve the sugar in the water. Cook over moderate heat without stirring until a medium-amber caramel forms, about 5 minutes. Off the heat, carefully add the butter and 1/2 cup of the balsamic vinegar. Return the saucepan to the heat and cook until the caramel is melted.
Add the onions, lemon zest, bay leaves and chicken stock to the saucepan and bring to a boil. Season with salt and pepper and simmer over moderately low heat until the onions are very tender and glazed and the liquid is syrupy, about 1 1/2 hours. Stir in the remaining 2 tablespoons of balsamic vinegar and season with salt and pepper.