Poke holes throughout the loins. Combine the next 10 ingredients in a non-reactive bowl. Place loins in bowl and toss to coat. Cover and refrigerate for 12 to 24 hours, turning occasionally. Place loins in a medium-low heat smoker or barbecue and slow-cook until internal temperature is about 150 degrees, about 1 1/2 hours. Remove and place in a baking dish, cover with onions and enchilada sauce and bake in a 375 degree oven for 1 hour or until meat starts to fall apart. Dip tortillas in pan sauce. Place pulled meat and a little cheese in each tortilla. Roll up and place seam side down in a baking dish. Top with remaining sauce and cheese and bake in a 375 degree oven until cheese is melted and lightly browned.