Preheat the oven to 350°F or get out the Crock-Pot or Instant Pot.
Place the chicken on a baking sheet or in the Crock-Pot/Instant Pot.
Sprinkle it with the cumin and chili powder.
Squeeze the juice of half of the lime over it and pour ½ cup of salsa over it.
Bake in the oven, covered for 1 hour or until done, or in the Crock-Pot/Instant Pot until done.
If reheating pre-cooked chicken:
Shred the chicken with your hands or a fork and place in a skillet.
Sprinkle with the cumin/chili powder, pour salsa over, and squeeze half of the juice of the lime over it.
Saute over medium heat until heated.
Prepare the toppings:
While chicken is heating, make guacamole (recipe here) or slice the avocados, wash and chop the salad greens, chop the tomato and onion, shred the cheese, get out the sour cream, heat up the beans, and make the cilantro lime rice if using.
Serve the chicken atop a bed of lettuce with any desired toppings.