Clean the casings, rinse well with water, then pour vinegar through them. Set aside. Use a food processor or the coarse blade of a meat grinder, grind the meat and fat.Add the onions, garlic, vinegar, tequila and seasonings, using the hotness of chile powder your family and guests will prefer. Stuff the casings. First cut the casings into 3-ft lengths and tie one end together. Use either a funnel or filling tube to fill the lengths.Tie at about 4-inch intervals with heavy thread. Place on a cookie sheet covered with wax paper. Set on the counter for about 2 hours, then refrigerate.After a day, freeze what you will not use within a week or two. Mixture should ripen for at least 8 hours before using.