Heat oil in a saute pan over medium high heat until shimmering. Add ground turkey (or chicken) and saute until browned, breaking up chunks and stirring with a long spoon frequently, about 4-6 minutes. Drain, then add the meat to the bottom of a slow cooker.
Add remaining ingredients (except the toppings) to the slow cooker, and stir to combine. Cover and cook on high heat for 4 hours or until the onions are soft and translucent. Season with salt and pepper if needed. Serve warm with desired toppings.
Notes
*I do not recommend using taco seasonings with extra preservatives and unknown ingredients. If you do not have a trusted taco seasoning, you can substitute the following:
-1 Tbsp. chili powder
-1 tsp. garlic powder
-1 tsp. black pepper
-1 tsp. cumin
-1 tsp. salt
-1/2 tsp. paprika
-1/4 tsp. onion powder