Preheat your oven to 350°F (175°C).
In a large skillet over medium heat, cook the ground beef until it is browned and fully cooked, breaking it up into crumbles with a spatula as it cooks. Drain any excess fat.
Stir in the taco seasoning according to the package instructions. Typically, this involves adding about 1/4 cup of water to the skillet and letting the mixture simmer for a few minutes until the sauce thickens.
Add the drained black beans and corn to the skillet, stirring to combine with the seasoned meat.
Spread a layer of crushed tortilla chips across the bottom of the 9x13 inch baking dish.
Spoon the meat mixture evenly over the layer of tortilla chips. Next, spread the diced tomatoes with green chilies over the meat mixture. Add a layer of sour cream on top, spreading it evenly with a spatula.
Sprinkle the shredded cheddar cheese evenly over the sour cream layer.
Place the baking dish in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.
Once baked, remove the casserole from the oven. If desired, top with sliced black olives, chopped green onions, and fresh cilantro. Serve hot with a side of salsa and extra tortilla chips for added crunch.