Cut pork shoulder into large chunks
Season with salt, pepper, cumin, oregano, garlic, and chili powder
Heat oil in a large pot or Dutch oven
Sear the pork on all sides until browned
Add onion, garlic, orange juice, and enough water or broth to partially cover the meat
Bring to a simmer
Cover and cook on low heat until the pork is very tender
Remove the pork and shred it with forks
Strain or reserve some cooking liquid
Spread the shredded pork on a baking sheet
Spoon a little cooking liquid over the pork
Broil or bake until the edges are crispy
Serve with tortillas, onions, cilantro, and salsa