- 1 medium red onion
- 1 cup orange juice
- 1/2 cup balsamic vinegar
- 1 to 2 tablespoons sugar
- Halve onion through root end and cut crosswise into very thin slices. In a 1 1/2-quart heavy saucepan simmer onion with orange juice and vinegar, stirring occasionally, until liquid is reduced and thickened, 30 to 40 minutes. Stir in sugar and salt to taste and cook mixture over low heat, stirring, until sugar is dissolved. Serve sauce warm or at room temperature.