Cook meat and soup bone separately until tender in enough water to keep covered. Dice roast, strain stock, and add the cooked beans.Stir in the Mexene and cumin seeds. Add salt and pepper (black and red) to taste. Cook very slowly over low flame 1 to 1 1/2 hours. AUTHOR'S NOTE: Leftover roast beef will do a good job too, as will canned pintos.