I got this online at Amazing Ribs. I've not tried it but it sounds great. Meathead says, "Here's a very tasty formula inspired by the sauce at legendary Cooper's Old Time Pit Bar-B-Que in Llano, TX":
1 tablespoon paprika
2 teaspoons black pepper
2 teaspoons American chili powder
1 teaspoon cumin powder
1 tablespoon of butter *
1 medium onion, finely chopped
4 cloves garlic, minced or pressed
1 green bell pepper, chopped
1 cup Lone Star beer (or any other lager). Drink any that is left over.
1/4 cup ketchup
1/4 cup apple cider vinegar
3 tablespoons Worcestershire sauce
3 tablespoons steak sauce
2 tablespoons brown sugar
Hot sauce to taste (start with 2 teaspoons of Tabasco sauce for mild heat)
2 cups beef, veal, or chicken stock
Note about the oil. Butter or margarine work fine, but to make it authentic, use rendered beef fat from the fatback of a brisket or use bacon fat.
1) Mix the paprika, black pepper, American chili powder, and cumin in a small bowl.
2) In a one quart saucepan, melt the butter or bacon fat and gently cook the onion over medium heat until translucent.
3) Add the garlic, bell pepper, and the spice mix you made in step (1). Stir, and cook for two minutes to extract the flavors.
4) Add the stock and the rest of the ingredients. Stir until well blended. Simmer on medium for 15 minutes. Leftovers will keep in the fridge for a month or so.
