Heat olive oil in a large skillet. Add onion and saute until cooked, for about 5 minutes.
In the same skillet, add turkey, cumin, coriander, chili powder, black pepper, and water. Stir to mix. Add salt to taste if needed.
Cook for 3-5 minutes until the turkey is warmed through and most of the water is evaporated. Remove heat and assemble into tortillas. Add your favorite toppings.