1. Heat oil in large nonstick skillet over medium heat until hot. Add onions and garlic; cook and stir 5 minutes or until onion is tender. Stir in vinegar, brown sugar, ginger and red pepper; cook and stir 2 to 4 minutes or until sugar is dissolved and mixture is thickened. Stir in tomatoes; cook 8 to 10 minutes or until sauce is thickened, stirring occasionally.
2. Remove from heat; stir in salt. Cool. Serve at room temperature.