1 med. onion, cut up
1 (8 oz.) can tomato sauce
2 tbsp. cider vinegar
2 garlic cloves, minced
3 level tbsp. chili powder (reduce amount if "hot")
1/2 tsp. dried oregano leaves
1/4 tsp. ground cumin
4 med. skinless chicken breast halves

Blend all ingredients except chicken. In 10-inch skillet over medium-high heat, bring to a boil. Reduce heat, add chicken, cover and simmer 25 minutes. Serve over rice.