Preheat your oven to 350°F (175°C).
In a large skillet, brown the ground beef over medium heat.
Stir in the taco seasoning and water, cooking until well mixed and thickened.
Add the black beans, corn, and salsa to the skillet, combining thoroughly.
In a greased 9x13 inch baking dish, layer half of the crushed tortilla chips evenly on the bottom.
Spread the beef and vegetable mixture over the tortilla chips.
Top with the remaining tortilla chips and sprinkle with cheese.
Bake for 25-30 minutes or until the cheese is bubbly and golden brown.
Remove from the oven and let cool for 5 minutes before serving.
Garnish with sour cream and sliced green onions before serving.