Combine all ingredients except tortillas in a slow cooker. Cook on low 6 hours or on high 4 hours. Shred chicken with two forks.
Fill tortillas with chicken mixture. Top with additional toppings, if desired.
Freezing Instructions
To use as a freezer meal, combine all ingredients except tortillas and optional toppings in a one gallon zip top freezer bag. When ready to use, place frozen meal in slow cooker and cook for 6 hours on high or 8 hours on low. Shred chicken. Fill tortillas with shredded chicken mixture and optional toppings.
Instant Pot®
Add all ingredients except tortillas and optional toppings in Instant Pot. Lock lid. Set valve to sealing. Program for manual-high, 22 minutes. Shred chicken. Fill tortillas with shredded chicken mixture and optional toppings.
Note: if freezing for the Instant Pot, freeze in a freezable container that fits inside the Instant Pot, see notes.