Preheat oven to 375 degrees. Spray a 9x13 baking dish with non-stick spray.
Add the ground beef and onion to a large skillet and cook, breaking the meat up as it cooks, until the beef is cooked through. Drain the fat, and stir in the taco seasoning to coat. Add the beef mixture to a large mixing bowl.
Add the beans, corn, green chiles, cream of chicken soup, and taco sauce to the bowl and stir well to combine.
Spread the beef mixture into the prepared baking dish. Sprinkle with the cheddar.
Arrange the tater tots in an even layer over the cheese.
Bake for 45 minutes or until the tater tots are golden brown and crispy.
Southwest corn is a mix of corn and peppers, also called Mexi-corn or fiesta corn.