Finely chop 1/3 red onion and adobe peppers and place in crockpot. Add adobe sauce, beef broth, spices, minced garlic, and apple cider vinegar, and mix well.
Trim excess fat off the meat and cut into large chunks. Nestle the meat in the broth and cover.
Cook on low for 6-8 hours or on high for 4-6.
When meat is done it should shred easily with a fork or even break apart when you gently press on it. Shred all the pieces of meat, mix well and let simmer on low for another 10-15 minutes while you prepare the salsa and toppings.
In a medium bowl, combine the rest of the chopped red onion, 1 cup pickled jalepeńos, and 1/2 cup chopped cilantro. I added some salt because I like everything salty.
For tacos, add meat to lettuce leaves or small tortillas. Top with cheese, jalapeño salsa, tomatillo sauce, and sliced avocado.