Carnitas for Enchiladas Rojas

Combine pork, garlic and salt in a 10-inch cast-iron skillet. Add 2 cups water; bring to a boil. Reduce heat and simmer, turning occasionally, until water has evaporated, about 1 hour; pork will begin to brown in its own fat. (If using leaner part of shoulder, add 1 to 2 tablespoons safflower oil.) Increase heat to medium and cook pork on all sides, turning and scraping up crisp bits with a spatula, until browned and tender, about 15 minutes. Coarsely shred with two forks.