Heat oil in a large skillet over medium high heat until it starts to shimmer. Pat chuck roast dry and sear on both sides.
Add honey, diced chipotle pepper in adobo, chipotle in adobo sauce, garlic powder, onion powder, cumin, kosher salt, and freshly ground black pepper to slow cooker and stir together. Place chuck roast in slow cooker and turn to coat in honey chipotle mixture. Pour in beef broth. Cover and let slow cook for 8-9 hours on low or until tender.
Once beef is fork tender, shred and mix with juices to keep moist. Squeeze fresh lime juice over meat and sprinkle with fresh cilantro.
Thinly slice a small red onion and place in a pint sized (16 oz) mason jar. In a small pan, bring 1 cup of apple cider vinegar to a boil. Add sugar, salt, and crushed red pepper to pan and stir to dissolve. Remove from heat and carefully pour over red onions. They can be served right away, or let cool, cover with mason jar lid and store in refrigerator.
In a small blender or food processor, combine avocado, water, olive oil, cilantro, lime juice, garlic clove, and kosher salt. Taste and adjust seasoning as needed.
Warm flour tortillas or fry corn tortillas. Fill tortillas with shredded beef and top with pickled onions, creamy avocado sauce, and queso fresco, if desired.
Adjust kosher salt amount depending on size of chuck roast. I use Morton's Coarse Kosher Salt. The recommended seasoning for beef is about 1 teaspoon of kosher salt per pound. For a 3 pound roast, I recommend using 2 1/2 teaspoons in the recipe to account for the sodium in the beef broth. If using a smaller roast or larger roast, you should decrease or increase the amount of kosher salt accordingly. If using table salt, reduce the suggested amount by half to account for the different size of salt crystals.