Cut the pork shoulder into large chunks, seasoning generously with salt, pepper, and cumin.

In a skillet over medium heat, sauté chopped onions until translucent. Add minced garlic and stir for one minute.

Transfer the seasoned pork, sautéed onions, and garlic to a slow cooker. Cook on low for 8 hours or high for 4 hours until tender.

Preheat oven to broil. Place jalapeños on a baking sheet and roast until charred on all sides (about 10 minutes).

In a blender, combine roasted jalapeños (seeds removed), avocado flesh from two avocados, lime juice from one lime, and cilantro. Blend until smooth; season with salt.

Shred cooked pork using forks. For extra crispiness, spread shredded meat on a baking sheet and broil for an additional five minutes.

Serve in warm tortillas topped with jalapeño lime avocado sauce and chopped cilantro.