1/4 c. cider vinegar
6 tbsp. dark brown sugar
6 tbsp. lemon juice
1 tsp. dry mustard
1 tsp. salt
1/2 tsp. pepper
1/2 c. water
2 lb. pre-cooked boneless ham, cut into 1/16" slices

In a 12-inch skillet, mix all ingredients except ham. Stir over moderately high heat until sugar and mustard are dissolved. Add ham slices in an even layer. Cook about 10 minutes, turning ham slices 2 or 3 times, until most of liquid has evaporated and only a small amount of thick syrup remains in pan. Turn ham in syrup to coat.