Combine the dry spices to make the rub: salt, oregano, cumin, garlic powder, onion powder, cayenne.
Rub the pork shoulder all over with the mix and place in the slow cooker.
Add the chicken stock, chipotle peppers in adobo, lime juice, diced onion, and 1/3 of the pineapple cut into small chunks. I also place the outer skin of the pineapple over the top of the meat while cooking.
Cover and cook on high for 5 hours or low for 10 hours.
Remove the meat from the slow cooker and shred, this should be easy to do with two forks.
Fill tacos shells with the meat and top with diced onion, pineapple and chopped cilantro.
Notes
Pork shoulder is also called Boston butt, picnic shoulder and picnic roast. If you can’t find this or want a pork substitute a good alternative is beef chuck roast.
I don’t trim the fat before slow cooking. I find leaving it on adds tenderness to the final dish. I also think it’s easier to remove any large fat sections during the shredding process.
You can use water instead of chicken stock. If you do I’d recommended adding a little more salt, maybe 1/2 teaspoon or more.
I love this al pastor right out of the slow cooker once shredded. But if you want to add some texture or crispy ends you can quickly pan fry it in a little oil, much like my carnitas recipe.
Al pastor meat makes great leftovers! Store in an airtight container in the refrigerator for at least 3 days. You can easily rewarm it on the stovetop or microwave.