Preheat the oven to 375°F (190°C).

Dice the onion and drain and rinse the black beans.

Crush the tortilla chips into small pieces and set aside.

In a large skillet, cook the ground beef and diced onion over medium heat until beef is browned and onion is soft, about 5-7 minutes.

Drain excess grease from the skillet.

Add the taco seasoning mix and water to the skillet, stirring to combine. Simmer for 3-4 minutes until the sauce thickens.

Stir in the corn and black beans, then remove from heat.

Spread the beef mixture evenly in a 9x13 inch baking dish.

Sprinkle shredded cheddar cheese over the top, then add crushed tortilla chips and Monterey Jack cheese.

Bake uncovered for 15-20 minutes until cheese is melted and bubbly.

Remove from oven, garnish with chopped cilantro, and serve with sour cream and salsa on the side.