2 tablespoons olive oil  | 
                                                2 3/4 cups finely chopped onions  | 
                                                1 tablespoon minced garlic  | 
                                                2 15-ounce cans black-eyed peas, drained  | 
                                                2 1/4 cups low-salt chicken broth  | 
                                                2 8-ounce cans tomato sauce  | 
                                                2 1/2 teaspoons dried oregano  | 
                                                large pinch of cayenne pepper  | 
                                                1 teaspoon red wine vinegar  | 
                                                freshly grated parmesan cheese  |