Preheat InstaPot using the SAUTE function.
Season beef with salt and pepper and sear in the pot with oil until browned on all sides- about 7 minutes.
Add remaining ingredients, except for the tortillas, cheese and garnishes. Cook on MEAT function for 30 minutes or until you can easily shred the beef with a fork.
Remove beef from the liquid, shred with a fork and discard excess fat. Season with salt, pepper and reserve.
Meanwhile, reduce the broth until thickened and skim off excess fat – about 10 minutes. Drizzle some of the reduced liquid over the shredded beef.
Preheat a large skillet over MEDIUM-HIGH heat and drizzle with a small amount of oil.
Dip tortillas in the broth and place in skillet. Top with shredded beef and cheese (optional).
Griddle until crispy and fold in half. Continue to cook until lightly charred- about 1 minute per side.
Garnish with more of the leftover sauce, onion, cilantro and a lime wedge.
If using a crock pot or oven, sear beef separately before placing in the pot. Cover and cook for 4-5 hours on LOW heat or 250F, until fork tender.Print Recipe