Prepare the chicken: In the bowl of your crockpot, combine the chicken, onion, enchilada sauce, chipotle peppers, oregano, cumin, and salt. Cover and cook on LOW for 4 hours or HIGH for 2-3 hours.
Shred the meat: Once the chicken is tender, shred it with two forks and mix it back into the sauce to soak up all the flavor.
Crisp up the tacos: Preheat your oven to 425° F. Warm the corn tortillas in the microwave for 30 seconds to make them pliable. Rub each tortilla with a little olive oil, then fill with cheese and chicken tinga. Fold the tortillas in half, pressing gently to seal.
Bake: Arrange the tacos on a baking sheet and bake for 5-8 minutes. Flip and bake for another 5 minutes, or until the tortillas are golden and crispy.
Make the crema: In a blender, combine avocados, pickled jalapeños, cilantro, honey, garlic, lime juice, and a pinch of salt. Blend until creamy.
Assemble the tacos: Serve the tacos hot, topped with avocado crema, shredded lettuce, and pickled onions. Add a squeeze of lime for extra brightness.