In a blender or food processor, grind the jalapenos and peeled garlic to a pulp. Add all the other ingredients, except the meat, and blend well. Cut the meat into 1-inch cubes and place in a large bowl, and cover with the marinade. Marinate overnight or all day. Place the meat on skewers and cook on the grill over mesquite wood, basting frequently with the sauce.
Serve with warm flour tortillas and plenty of Mexican beer with lime slices.
