Toppings: Salsa, sour cream, Cotija cheese, cubed avocado and chopped green onions
Preheat oven to 400°. Scrub potatoes; pierce each several times with a fork. If desired, rub with oil. Bake until tender, 50-75 minutes.
Meanwhile, in a large skillet, cook beef over medium heat until no longer pink, 6-8 minutes, breaking into crumbles; drain. Stir in taco seasoning and water; bring to a boil. Reduce heat; simmer, uncovered, until thickened, 3-4 minutes, stirring occasionally.
With a sharp knife, cut an "X" in each potato. Fluff pulp with a fork; season with salt and pepper. Spoon beef mixture over top. Serve with toppings.