Place the chicken thighs into the slow cooker.
Top with crushed red pepper, oregano, cumin, garlic powder, cilantro, and onions. (add anchiote paste for heat if you want)
Over the top, pour the oil and juices.
Cook on hight for 4 hours.
Serve chicken sliced with corn tortillas, salsa, cheese, and guacamole (optional).
To prepare this meal for the freezer, place all ingredients in a gallon freezer bag. Thaw the night before in the refrigerator. Cook as directed above.