A slow cooker version of the Mexican classic, Tacos al Pastor is made with pork shoulder simmered in an aromatic mixture of pineapple, chiles, garlic and spices.
Place pork shoulder in a slow cooker and top with 1 cup of the diced pineapple and the diced onion; set aside.
Remove seeds and stems from dried chilis and place in a large bowl. Cover with boiling water and let steep to soften, about 15 minutes.
Place softened chilis along with 1 cup of the reserved steeping liquid in a large food processor. Add the remaining 1 cup diced pineapple, quartered onion, lime juice, achiote paste, vinegar, garlic, cumin, oregano, salt and pepper. Puree on high for 60 seconds.
Drain mixture over a fine mesh strainer placed directly on top of the pork shoulder in the slow cooker insert. Use a rubber spatula to press out all of the liquid and discard what's left in the strainer.
Cook pork on high for 4 hours or low for 8 hours.
To serve, shred pork with two forks discarding any large pieces of fat. Serve in warmed corn tortillas with cilantro, minced onion, minced pineapple and any other toppings of choice.
Notes
We usually leave the seeds in the chilis as the kick of heat balances perfectly with the sweet pineapple but if you want to keep this mild, simply remove the seeds before steeping the chilis. Leftovers freeze great!!