Prepare the Filling: In a large skillet, cook the ground beef (or your choice of protein) over medium heat, breaking it apart with a spatula. Add the chopped onion and cook until softened, about 3–4 minutes. Drain any excess grease.
Stir in the taco seasoning and water. Let the mixture simmer for 3–4 minutes until thickened and the flavors are well combined. Remove from heat and set aside.
Warm the Tortillas: Heat the tortillas in a dry skillet for about 30 seconds on each side, just until warm and flexible. Alternatively, you can microwave the tortillas in a damp paper towel for 20-30 seconds.
Assemble the Tacos: Lay a tortilla flat and spoon 2 tablespoons of the beef mixture onto the center. Sprinkle with about 1–2 tablespoons of shredded cheese. Roll the tortilla tightly around the filling and place it seam-side down on the prepared baking sheet. Repeat with the remaining tortillas and filling.
Bake the Tacos: Lightly spray the tops of the rolled tacos with cooking spray or drizzle with a bit of olive oil. Bake for 15-20 minutes, or until the tacos are crispy and golden brown.
Serve: Remove the tacos from the oven and serve immediately with sour cream, salsa, and any optional garnishes you like.
Enjoy!