Ingredients

• 1 small onion, finely chopped
• 1 tablespoon vegetable oil
• 1 pound black plums (4), pitted and coarsely chopped
• 1 1/4 cups water
• 1/4 cup plum jam
• 2 teaspoons balsamic vinegar
• 2 teaspoons Dijon mustard
• 1/4 teaspoon black pepper
• 1/4 teaspoon salt

Instructions

1. Cook onion in oil in a 3- to 4-quart heavy saucepan over moderate heat, stirring occasionally, until golden, about 5 minutes. Stir in remaining ingredients and simmer, uncovered, stirring more frequently toward end of cooking, until plums fall apart and sauce is thickened, about 1 hour. Cool to room temperature. Serve with pork or chicken.