1/2 cup onions, chopped
1 1/2 tbsp. brown sugar
1 tbsp. vegetable oil
1 whole lemon, unpeeled and quartered
1/4 cup cider vinegar
1/3 cup ketchup
1 tbsp. prepared horseradish
1 tbsp. water
1/2 tsp. coarsely ground black pepper

Cook onion and brown sugar in vegetable oil over medium heat about 3 minutes, or until onion is tender. Add remaining ingredients, including lemon quarters, and continue cooking over medium heat for another 5 to 10 minutes, stirring occasionally. Remove from the heat, cool thoroughly and remove lemon pieces. Add meat or poultry to the marinade; let marinate in the refrigerator for at least two hours, or up to 6 hours. Turn meat occasionally during marinating so that all sides are equally exposed to the marinade. Brush the remaining marinade on the meat during grilling. To use the remaining marinade as a sauce, be sure to bring it to a rolling boil for at least one minute prior to serving.