To a blender, add 1 1/2 cups low-sodium chicken broth, 7 ounces canned chipotle peppers in adobo, 16 ounces canned crushed pineapple, and 1 packets Sazón seasoning with coriander & annatto. Cover and blend until smooth to make the marinade. Set aside.
Cut the 2 pounds pork sirloin roast into quarters. In a bowl, combine the 2 teaspoons salt, 1 teaspoon black pepper, and 3 packets Sazón seasoning with coriander & annatto. Rub the spice mix all over the pork piece and then set aside.
Turn the Instant Pot to saute and cook the diced 8 ounces thick-cut bacon until crispy, about 3-5 minutes, stirring frequently. Add the pork pieces to the Instant Pot and brown on all sides, about 5 minutes. Turn off the pot. Holding a piece of paper towel with tongs, soak up any excess grease in the pot.
Pour the al pastor marinade over the pork roast and stir as best you can to loosen any fond on the bottom of the pot.
Lock the Instant Pot lid in place, set it to sealing, and set the pot to high pressure (manual) for 35 minutes.
Once the cooking time is up, let the pressure naturally release for 10 minutes, and then carefully quick-release the rest. Use an instant-read thermometer to check that the pork has an internal temperature of 145 degrees F. *Pro Tip: If it's up to temp but still feels tight, add a few more minutes under pressure. Reseal the Instant Pot and cook for another 5-10 minutes.
Remove the pork roast from the pot and shred it on a cutting board with a couple of forks. Then return the pork to the sauce and stir to combine.
Serve warm in corn tortillas, with chopped white onion, cilantro, and pineapple chunks on top, and lime wedges for garnish.
Notes
Nutritional information is based on 1/4 pound of al pastor meat, 1 tortilla, 1 tablespoon of onion, 1 tablespoon of cilantro, and 2 tablespoons of pineapple chunks per taco.
A sirloin pork roast will be about 2 to 4 pounds. This recipe can accommodate up to a 4-pound roast.
Remove seeds from the chipotle peppers and/or rinse off the adobo sauce for a milder marinade.
If you prefer to use achiote paste, substitute about 2 tablespoons of paste per 1 packet of Sazón seasoning. One 3.5-ounce box of paste will be enough.