Place the chicken breasts into the Instant Pot or slow cooker.
In a small bowl, combine the ancho chili powder, cumin, coriander, ¼ teaspoon salt, and ¼ teaspoon black pepper.
Sprinkle the seasoning mixture evenly over both sides of the chicken. Add the minced garlic, then pour the fire-roasted salsa over the chicken, making sure it is well coated.
Instant Pot Method
Secure the lid and set the valve to Sealing. Cook on the Poultry setting or Manual High Pressure for 13 minutes.
When the cooking cycle finishes, carefully perform a quick pressure release according to the manufacturer's instructions.
Slow Cooker Method
Cover and cook on Low for 5 to 6 hours or until the chicken is tender and easily shreds with a fork.
Transfer the cooked chicken to a cutting board and let it cool for several minutes.
Using two forks, shred the chicken into bite-sized pieces.
Return the shredded chicken to the cooking juices and stir in the chopped cilantro. Taste and adjust seasoning with additional salt and pepper if needed.
Using tongs, lift the chicken from the juices and fill each warmed tortilla.
Top with shredded lettuce, diced tomatoes, cheese, avocado or guacamole, sour cream, and your favorite hot sauce before serving.