1. Preheat the oven to 400°F and lightly grease a 9×13-inch baking dish.

2. In a large skillet over medium heat, cook the ground beef and chopped onion until the beef is browned and the onion is soft. Drain any excess grease.

3. Stir in the minced garlic and cook for 30 seconds.

4. Add the taco seasoning, drained diced tomatoes with green chiles, black beans, corn, and water. Stir well and simmer for 3 to 4 minutes.

5. Spread the beef mixture evenly into the prepared baking dish.

6. Arrange the frozen tater tots in an even layer over the top.

7. Bake for 30 to 35 minutes, or until the tater tots are golden and crisp.

8. Sprinkle the shredded cheddar cheese over the top and return the dish to the oven for 5 minutes, or until the cheese is melted.

9. Remove from the oven and top with sliced black olives, diced red bell pepper, and sliced green onions before serving.