Whisk together the dry seasoning mix. Rub the pork butt down with the seasoning.
Select ‘saute’ on the Instant Pot and add the olive oil to the pot insert. Roast the pork on all sides, in batches as necessary, for approximately 4 minutes each side to get a nice brown sear.
Remove the meat and set aside on a plate. Deglaze the pot insert with the Mezcal, scraping up the browned bits. Add the remainder of the cooking liquid to the pot, and turn off saute mode.
Set the trivet into the bottom of the pot and layer the pieces of pork on top. Nestle the bell pepper and jalapenos slices around the meat.
Seal the Instant Pot and pressure cook for 30 minutes. Let the carnitas naturally vent for 10 minutes, and then manually vent the rest of the way.
Meanwhile, heat the oven to 425 degrees F and line a baking sheet with heavy duty foil. While the pork is cooking, prepare the salsa and stir together in a bowl. Set aside.
When the pressure cooker has fully vented, remove the pork from and shred it (I like to use these awesome bear claws). Return the pulled pork to the liquid in the pot and stir, coating the meat. Using a slotted spoon or tongs, transfer the pulled pork to the prepared baking sheet and bake for 10 minutes until the edges are crispy and caramelized.
Divide the pulled pork among the tortillas, top with your favorite ingredients, and serve immediately. Left over pork can be stored in the fridge for up to 3 days. To reheat, spread out on a baking sheet as above and cook under the broiler to about 5 minutes.