In a nonreactive sauce pan, heat the olive oil over medium heat. Saute the onions and garlic until translucent. Add the remaining ingredients. Bring the mixture to a boil, stirring often. Reduce the heat to a simmer. Simmer over medium heat for 10 minutes or reduced by 1/4. Note: If you don't use all of the sauce, put it in a clean jar and seal. The sauce will keep very well for 2-3 months if refrigerated.