In a skillet, cook ground beef and chopped onion over medium heat until beef is browned. Drain excess fat.
Add taco seasoning to the beef mixture and cook according to the packet instructions.
In a baking dish, layer tortilla chips, beef mixture, black beans, corn, salsa, and shredded cheese. Repeat layers until all ingredients are used, ending with a layer of cheese on top.
Bake in preheated oven for 20-25 minutes, until cheese is melted and bubbly.
Remove from oven and let cool for a few minutes. Top with sour cream before serving.