1Cut the pork shoulder into large chunks.
Remove the stems and seeds from the dried ancho and guajillo chiles. Soak them in hot water for about 20 minutes until they are soft.
In a blender, combine the soaked chiles, apple cider vinegar, orange juice, chopped onion, garlic cloves, cumin, oregano, and a pinch of salt. Blend until smooth to create the marinade.
In a large pot, heat the vegetable oil over medium-high heat. Add the pork chunks and brown them on all sides.
Pour the marinade over the browned pork. Reduce the heat to low, cover the pot, and let it simmer for about 2 hours, or until the pork is tender and can be easily shredded.
Once the pork is tender, shred it using two forks. Mix the shredded pork with the sauce in the pot.
Adjust the seasoning with salt to taste.
Serve the chilorio with warm tortillas, rice, or beans as desired.