In a large skillet over medium heat, brown the ground beef and diced onion until the beef is cooked through and the onion is translucent, about 5-7 minutes. Drain any excess fat.

In a large bowl, combine the cooked beef and onion mixture with corn, black beans, cream of mushroom soup, garlic powder, chili powder, salt, and pepper. Mix until well combined.

Spray the slow cooker with non-stick cooking spray. Pour the beef mixture into the slow cooker and spread it evenly.

Top the beef mixture with frozen tater tots, arranging them in a single layer.

Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the tater tots are golden brown and crispy.

In the last 30 minutes of cooking, sprinkle the shredded cheddar cheese over the tater tots. Cover and let the cheese melt.

Serve hot, garnished with fresh cilantro or green onions if desired.