Start by dicing half a red onion. Sauté with 1 and 1/2 tablespoons of butter in a medium sauce pan. Sauté for about 5 minutes or until onion is translucent. Next add two 16-ounce cans of Black Beans (do not rinse). Add 3/4 of a cup of Borracho Cooking Sauce. Bring to a boil, then cover and simmer on low heat for 25 minutes to allow the flavors to meld. Top and serve with a shredded or crumbled mexican queso.