Add 1 cup salsa of choice, 2 tablespoons taco seasoning, and salt (only if your taco seasoning doesn't contain salt already) to Crockpot. Stir to incorporate ingredients.
Add 3 large boneless, skinless chicken breasts. Flip chicken to coat with salsa mixture, then place lid on Crockpot.
Cook chicken on LOW 5 to 6 hours, or on HIGH 3 to 3 ½ hours.
When cook time is up, transfer chicken to large bowl (or cutting board). Shred cooked chicken with hand mixer (or 2 forks), then return shredded chicken to Crockpot and stir to incorporate with salsa mixture.
Cook uncovered on LOW 60 minutes or on HIGH 30 minutes.
For the Avocado-Cilantro Sauce
Add 1 large avocado, 1 medium jalapeño pepper, ½ cup cilantro leaves, ½ cup water, 2 cloves garlic, 2 teaspoons white vinegar, and salt to food processor or blender. Pulse until ingredients are fully combined and mixture is very smooth. Taste and add more salt if desired.
To Warm the Tortillas
Wet paper towel and wring out majority of excess water. Spread paper towel out on microwave-safe plate, then place one flour tortilla on top of paper towel. Repeat, layering damp paper towels and tortillas on plate, until all tortillas have been stacked on plate. Cover last tortilla with one damp paper towel.
Place plate in microwave. Microwave 20 to 30 seconds or until tortillas are warm and softened, then carefully remove plate from microwave.
To Serve the Tacos
Portion shredded chicken into warmed tortillas. Drizzle avocado-cilantro sauce over chicken as desired, then top tacos with preferred toppings. Serve immediately.
Recipe Notes
To drizzle avocado-cilantro sauce, fill a plastic sandwich bag with prepared sauce. Snip off a small piece of one corner and drizzle sauce over chicken in tacos.
Shred Chicken: Watch this quick video to see how to shred chicken with a hand mixer.
Make it Whole30: Use a Whole30-compliant taco seasoning and salsa. Replace tortillas with lettuce cups. Omit any cheese and sour cream.
Make it Paleo: Use paleo-friendly taco seasoning and salsa. Replace tortillas with lettuce cups, or use grain-free tortillas. Use paleo-friendly cheese.
Make it Gluten Free: Make sure your taco seasoning and salsa don't contain any hidden gluten. Replace tortillas with lettuce cups or use corn tortillas or gluten-free tortillas.
Make it Low Carb/Keto: Use a keto taco seasoning and a salsa without any added sugars or sugar substitutes. Replace tortillas with lettuce cups, low-carb tortillas, or homemade keto tortillas.