In your crockpot, pour in the enchilada sauce, tomatoes, black beans. Drop in the onion, chili powder, garlic, and cumin. Stir. Push the chicken pieces down into the liquid, put the lid on, and set to low for about 6 hours for frozen chicken, 4 hours for thawed. Once chicken is cooked through, shred with a fork.
Top with cheese and sour cream if you prefer. Its that easy!! And its super delicious!!