For the kid: Put kids in a large stockpot, and cover with water. Add salt and vinegar. Set aside for 2 hours. Meanwhile, build a pile of mesquite wood on the ground, and burn down to white coals. Remove kids from water and thread on spits. Arrange over the hot coals, and roast for 2 to 3 hours, depending on the kids' weight, basting occasionally with a little salted water. Turn spits continuously so that the meat cooks evenly, or use a rotisserie. Add more white coals if necessary. To serve, cut kid in pieces, and place on plates. Garnish with guacamole, onion, tomato, cilatro, and chiles. Serve withj Frijoles de Olla sprinkled with cheese, totopos, and Pico de Gallo sauce. The kid may be shredded and used in fried tacos. Makes 8 servings.