In a small bowl, make the spice mixture by combining the cumin, smoked paprika, garlic powder, chili powder, and salt, stirring to combine. Set aside.
In a large skillet, heat the olive oil over medium-high heat. Add the turkey, sprinkle with half the spice mixture, then stir, breaking the ground turkey apart with a wooden spoon.
Allow the turkey to brown on one side, about 4-5 minutes, then stir to flip the turkey and cook and additional 3-4 minutes until browned and cooked through
Carefully transfer the turkey to a 6-quart slow cooker. Add the remaining spice mixture and the tomato sauce, stirring to combine.
Cover and cook on high for 2-3 hours or low for 4-5 hours.
Serve in warm tortillas with preferred toppings if desired.
Notes
Optional Serving Suggestions: Tortillas, lettuce, tomato, avocado, jalapeno, hot sauce, salsa, cheese, sour cream, red onion
Heat Level: Skip the chili powder if you are sensitive to hea, or stir in a tablespoon of hot sauce at the end to kick up the heat.
Stovetop Variation: Follow step 1, then heat a large Dutch oven over medium-high heat. Follow steps 2-3, then add remaining spice mixture and the tomato sauce, stirring to combine. Bring to a simmer, cover, reduce the heat to low, and simmer for 20-30 minutes, stirring occasionally.