Peel and wash tomatillos, and place on a foil-lined cookie sheet. Add quartered onions, garlic, and peppers. Drizzle with one tablespoon olive oil. Broil on high for five minutes.
Meanwhile, chop pork into 2"-3" chunks, wash, and pat dry. Mix salt, pepper, and flour. Sprinkle the mixture over the meat. Work in until the meat is coated with the mixture.
Take the tray out of the oven, remove veggies that are charred. Flip the remaining vegetables and broil for an additional two to three minutes. Remove from the oven and allow to cool.
Heat the remaining olive oil in a cast-iron skillet. Sear pork, working in batches, and place in the Instant Pot.
Peel roasted garlic, and poblano peppers. Add to a blender, along with the other charred vegetables, and chicken stock. Depending on the size of your blender, you might have to do this in batches. Pulse the vegetables until roughly chopped.
Pour the mixture over the meat in the Instant Pot. Stir in the cumin, coriander, oregano, and cilantro.
Seal the Instant Pot and bring up to pressure (15 to 20 minutes). Cook on high pressure for 30 minutes. Vent manually, or allow the Instant Pot to vent naturally.
Serve with sour cream, warmed tortillas, shredded cheese, tortilla chips, and lime wedges.