Preparation Heat oil in large skillet over medium-high heat. Add onions, salt and pepper; cook until onions begin to brown, stirring frequently, about 8 minutes. Add broth, barbecue sauce and vinegar. Reduce heat to medium; simmer until sauce thickens, stirring occasionally, about 15 minutes. (Can be made 1 day ahead. Cover; chill. Rewarm before serving.)
Preparation Heat oil in large skillet over medium-high heat. Add onions, salt and pepper; cook until onions begin to brown, stirring frequently, about 8 minutes. Add broth, barbecue sauce and vinegar. Reduce heat to medium; simmer until sauce thickens, stirring occasionally, about 15 minutes. (Can be made 1 day ahead. Cover; chill. Rewarm before serving.)