Add olive oil to a large skillet and place over medium high heat. Add diced onions and turkey. Brown the turkey, and break up the meat with a wooden spoon until nice and browned, about 5 minutes.
TO MAKE ON THE STOVETOP: add in garlic, tomato sauce water, cumin, chili powder, oregano, paprika, cayenne pepper and salt. Stir to combine. Simmer over medium low heat for 10-15 minutes or until mixture begins to thicken up.
TO MAKE IN THE SLOW COOKER: Transfer to the slow cooker and add in garlic, tomato sauce, cumin, chili powder, oregano, paprika, cayenne pepper and salt. Stir to combine. Cook on high for 2-3 hours or on low for 6-7 hours.
Once ready to serve, divide meat between 8 corn tortillas. Add optional toppings: tomatoes, cheese, diced avocado/guacamole, lettuce and jalapeno. Serves 4. Optional to serve with greek yogurt, if desired.
To make dairy free: sub dairy free cheese or simply leave off the cheese.