Step 1: Prepare the Filling

1. Brown the Meat: Heat a large skillet over medium-high heat. Add a drizzle of olive oil or cooking spray. Once hot, add the ground beef (or your chosen meat substitute). Cook, breaking it up with a spoon, until browned and no longer pink. Drain off any excess grease.
2. Sauté Aromatics (Optional): If using, add the chopped onion and bell pepper to the skillet with the browned meat. Cook for about 5-7 minutes, or until the onion is softened and translucent and the bell pepper is slightly tender. Add the minced garlic (or garlic powder) and cook for another minute until fragrant.
3. Season and Simmer: Stir in the taco seasoning and water (or beef broth) into the skillet with the meat and vegetables. Bring to a simmer, then reduce heat to low. Add the diced tomatoes (undrained), black beans (rinsed and drained), and corn (drained). Stir to combine all ingredients.
4. Simmer and Thicken: Let the filling simmer for about 10-15 minutes, stirring occasionally, allowing the flavors to meld and the sauce to slightly thicken. Taste and adjust seasoning with salt and pepper as needed. If you prefer a thicker filling, you can simmer for a bit longer or add a tablespoon of cornstarch slurry (cornstarch mixed with a little cold water) towards the end of cooking.

Step 2: Assemble the Taco Pie

1. Preheat Oven and Prepare Baking Dish: Preheat oven to 375°F (190°C). Lightly grease a 9-inch pie dish or a similar-sized oven-safe skillet (cast iron works beautifully).
2. Layer the Tortillas: Arrange the flour tortillas in the bottom of the prepared baking dish, overlapping them slightly to cover the bottom and come up the sides of the dish, creating a tortilla crust. You can trim any excess tortilla overhang if desired. If using corn tortillas, you might need to slightly overlap them more to prevent gaps.
3. Add the Filling: Pour the prepared taco meat filling evenly over the tortilla crust in the baking dish.
4. Top with Cheese: Sprinkle the shredded cheese evenly over the taco meat filling. Make sure to cover the entire surface for a beautifully melted and cheesy topping.

Step 3: Bake the Taco Pie

1. Bake: Place the Taco Pie in the preheated oven and bake for 20-25 minutes, or until the cheese is melted, bubbly, and lightly golden brown around the edges. The tortillas should be slightly crisp and the filling heated through.
2. Rest (Optional): Let the Taco Pie rest for a few minutes before slicing and serving. This allows the filling to set slightly and makes it easier to slice.
3. Garnish and Serve: Garnish with fresh cilantro (if desired) before serving.