Add all the ingredients into the slow cooker except for tortillas and toppings. Mix everything, making sure the spices and salsa mixture all cover the chicken breasts.
Cover and cook on high for 3 hours or for 6 hours on a low function.
Once the chicken is tender, shred it using two forks. Give the whole mixture a good stir and cook for an additional 1 hour. This time, keep the lid slightly ajar to let the moisture evaporate.
Slightly toast your tortillas on a stovetop. Do about 20-30 seconds per side until they brown up a little bit and warm. You can use a slight amount of oil.
Top each tortilla with chicken. Top up with avocado mash, sour cream, lime slices, and fresh cilantro. Serve immediately.
