Preheat your oven to 350°F (175°C).

In a large skillet over medium heat, cook the ground beef until fully browned. Drain any excess fat.

Add taco seasoning and water to the cooked beef, stirring until well combined. Allow to simmer for about 5 minutes or until slightly thickened.

Stir in salsa and let the mixture cook for an additional 2 minutes.

In a separate bowl, mix together the black beans and corn.

Spread a thin layer of the beef mixture across the bottom of a 9x13 inch baking dish.

Place a tortilla over the beef mixture, ensuring it covers the bottom of the dish evenly.

Spread a layer of the black bean and corn mixture over the tortilla.

Sprinkle a layer of cheddar and Monterey Jack cheese over the bean mixture.

Repeat the layering process: beef mixture, tortilla, black bean and corn mixture, and cheese until all ingredients are used, finishing with a layer of cheese on top.

Cover the dish with aluminum foil and bake in the preheated oven for 25-30 minutes.

Remove the foil and bake an additional 10 minutes until the cheese is bubbly and golden brown.

Remove from oven and let the dish cool for 5 minutes.

Top with sour cream, cilantro, and green onions before serving.

Slice into squares and serve hot, optionally with tortilla chips and guacamole.