Heat gas or charcoal grill. In 2-quart saucepan, heat oil over medium-high heat. Cook onion and garlic in oil, stirring occasionally, until soft. Add 2 cups orange juice and the vinegar; heat to boiling. Reduce heat; simmer uncovered until mixture is reduced to 1 cup. Remove from heat; stir in brown sugar, ketchup and molasses. Stir in desired amount of chiles. Set aside.