Step 1

Place ½ of the tomatoes, half of the chilies, and half of the onion in the bottom of a slow cooker. Place chicken on top.

Step 2

Sprinkle taco seasoning over chicken. Add remaining tomatoes, chilies, and onion on top of chicken.

Step 3

Cook on LOW for 4-6 hours or on HIGH for 2-3 hours.

Step 4

Remove the chicken to a cutting board and use two forks to shred the meat. Stir the shredded chicken back into the sauce and cook for a few more minutes, until warmed through.

Step 5

Place ½ of the tomatoes, half of the chilies, and half of the onion in the bottom of an Instant Pot or pressure cooker. Place chicken on top.

Step 6

Sprinkle taco seasoning over chicken. Add remaining tomatoes, chilies, and onion on top of chicken.

Step 7

Secure the lid on the pot. Close the pressure-release valve.

Step 8

Select “Poultry” or “Manual” setting. Set the time to 8 minutes for fresh chicken breasts, or 13 minutes for frozen chicken breasts. (These times are for typical 6-8 ounce chicken breasts. If yours are larger, add a couple of minutes.)

Step 9

When done, let the pressure naturally release for at least 5 minutes. After that, you can turn the valve to "vent" for quick release if you're in a hurry, or continue natural release.

Step 10

Remove chicken to a cutting board; shred with two forks.

Step 11

Return chicken to pot, stir, and serve.