Cook ground beef and onions in a large skillet over medium heat. Cook until meat browned and onions have softened, about 8 minutes.
Add tomato sauce salt, pepper, cumin, paprika, oregano, garlic powder, and onion powder. Stir and simmer for 2 minutes.
Pour beef mixture into a 9-inch x 13-inch baking dish. Top with tater tots, being sure to spread them out into a single layer.
Bake for 35 minutes. Remove from oven and sprinkle cheddar cheese all over the tater tots. Return to the oven and bake for another 10-15 minutes. The casserole is done when the tots are crispy, cheese is melted, and filling is bubbling.
Remove from oven and let cool 10 mins. Top with green onion, tomatoes, olives, and red onion. Serve warm.