Step 1

In a Crockpot, combine all ingredients and stir. Don't add water. Cover. Cook on low for 5 to 6 hours, or cook on high for 3-3 1/2 hours.

Step 2

Shred the chicken breasts with a hand mixer or with two forks. Return the shredded chicken to the Crockpot if you shredded it by hand. See Note for more detail.

Step 3

Stir shredded chicken together with the sauce. Cook uncovered on high 30 minutes or on low 60 minutes.

Step 4

Make the avocado-cilantro sauce: combine all ingredients in a food processor or blender and process until very smooth with additional salt to taste.

Step 5

Heat tortillas. By microwave: wrap all tortillas in a couple of very lightly damp paper towels and microwave about 20 seconds or until warm. By skillet: heat a medium or large skillet, preferably cast iron, over medium heat until warm. Working one at a time, add a tortilla and cook until light brown spots appear on the bottom side, about 15 seconds. Flip and repeat, cooking about 15 seconds. Repeat with remaining tortillas, covering in a clean kitchen towel to keep warm.

Step 6

Make tacos: use tongs to portion shredded chicken into warm tortillas. Drizzle avocado-cilantro sauce over. See Note for drizzle suggestions. Top with crumbled queso fresco or shredded cheese, chopped red onions, or other toppings, as desired.