Cube the chicken and add to a large resealable freezer bag.
Add the olive oil, lime juice, cilantro, garlic cloves, drained black beans and corn, minced purple onions, and seasonings.
On the day of cooking, take out of the freezer to thaw.
Dump the bag contents into a slow cooker. Cook on high for 4-5 hours.
Serve on flour tortillas with salsa, sour cream, and guacamole.