Rinse the tongue well and add it to the pot of your Instant Pot (or pressure cooker) with rough-chopped onion, garlic, 1 ½ tablespoon salt, and enough water to cover by two inches.
Put the lid onto the Instant Pot and turn knob to sealing.
Pressure cook on high for 50 minutes for a 4 lb tongue (a 3 lb tongue would likely be done in 40 minutes).
While tongue is cooking, slice onions and peppers.
Once time is complete, manually release pressure. Use a towel and be careful of the steam.
Once pressure is reduced, remove beef tongue from the Instant Pot and allow to cool enough to handle.
While the tongue cools, add 1-2 Tablespoons of oil to a large skillet and add onions and peppers, stirring only occasionally. The goal is to soften the vegetables and slightly blacken the exterior.
Once it’s cool enough to handle, carefully peel the skin off of the tongue. Yes, this is the strangest part, but it should come right off!
Slice or shred the meat as desired. If adding the meat to the vegetables, I recommend slicing it in ½ inch slices so it holds up in the pan.
Add all spices and the remaining salt (½ tablespoon) to the pan with the vegetables. Homesteading Hack: Add meat as well if pan frying for color.
Cook everything in the pan until coated with spices and slightly crispy. Serve in warm tortillas or over rice.