Place the chicken breasts in a large, resealable freezer bag.
Combine the olive oil, onion, garlic, chipotles, oregano, cumin, fire roasted tomatoes, salt and pepper in a blender. Blend until smooth and well combined.
Pour the blended sauce over the top of the chicken
Remove excess air, seal, and freeze.
Slow Cooker Instructions:
Thaw.
Cook on high for 3 to 4 hours or low for 4 to 5 hours in the slow cooker.
Instant Pot Cooking Instructions:
Thaw.
Set to cook on high pressure for 12 to 15 minutes, then do a natural release for 10 minutes.
Recipe Notes
Topping suggestions:
lettuce, sour cream or crema, avocado, green or purple onions, tomatoes, guacamole, salsa, black olives