In a blender, combine the orange juice, ancho chile, garlic, oregano, black pepper, cumin, vinegar and 1 ½ teaspoons salt. Blend until smooth. Spread the pork pieces over the bottom of a 6-quart slow cooker, then pour the chile mixture through a medium-mesh sieve over the meat. Cover and cook on high for 4 hours, until the meat is fall-apart tender.
Remove meat from the slow cooker, reserve liquid for enchiladas or another sauce. Use a fork and break apart pieces of the pork until all is shredded. Heat a skillet over medium high heat, add oil and place shredded pork into pan. Add 2 tablespoons of reserved liquid, cook for about 4-5 minutes, until pieces start to crisp and brown. Once you have a nice char, place on a warm tortilla and top with radish matchsticks, crispy onions and cilantro leaves and enjoy.