Generously season the beef with 1 teaspoon of salt and black pepper on all sides.
Heat the olive oil in a large skillet over medium-high heat. Working in batches, sear the beef chunks on all sides until browned. Transfer it to a slow cooker.
Blend the tomatoes, chipotle peppers in adobo sauce, onion, garlic, dried oregano, and the remaining 1 teaspoon of salt in a large blender until smooth.
Pour the tinga sauce into the slow cooker and gently stir to coat the beef. Cover and cook on high for 5 hours or on low for 7-8 hours.
Transfer the beef to a bowl, shred it with two forks, then add it back into the slow cooker. Stir to combine.
Serve with warm corn tortillas or flour tortillas, queso fresco, diced onion, and chopped cilantro.
Instant Pot Method
Generously season the beef with 1 teaspoon of salt and black pepper on all sides.
Heat the olive oil in the Instant Pot using the Sauté function. Working in batches, sear the beef chunks on all sides until browned. Turn the Instant Pot off.
Blend the tomatoes, chipotle peppers in adobo sauce, onion, garlic, dried oregano, and the remaining 1 teaspoon of salt in a large blender until smooth.
Pour the tinga sauce into the Instant Pot, close the lid, and pressure cook on high for 60 minutes. When the timer goes off, let the pressure release naturally for 10 minutes before manually releasing any remaining pressure.
Transfer the beef to a bowl, shred it with two forks, then add it back into the slow cooker. Stir to combine.
Serve with warm corn tortillas or flour tortillas, queso fresco, diced onion, and chopped cilantro.
Notes
Sear the meat. Take the time to sear the beef before adding it to the slow cooker or Instant Pot. This step adds depth of flavor and helps to lock in juices.
Adjust the spice level. Customize the heat by adjusting the amount of chipotle peppers in adobo sauce. Start with a smaller amount and add more to taste.
Blend the sauce well. Ensure your sauce is well-blended to create a smooth, cohesive flavor. You don’t want any chunks of tomato in there.