- Preheat the oven to 350 degrees.
- Add the ground beef to a large frying pan over medium heat. Cook until some of the fat releases, then add the diced onion. Fry the two together until the onions are soft and the beef is no longer pink.
- Add the diced tomatoes and corn and sprinkle with taco seasoning. Stir until well combined. Taste and season with additional salt and pepper, if needed. Remove from heat and stir in the sour cream and one cup of the cheese.
- Spread the meat mixture into a deep dish 9-inch pie plate or 8-inch square casserole dish.
- Top with the tater tots and the remaining cheese. Bake for 40-45 minutes, or until filling is bubbly and cheese is golden brown.
- Remove from the oven and serve. Top individual portions with avocados, tomatoes, sour cream, and cilantro.
To make ahead, follow steps 2-4 then refrigerate or freeze. When ready to bake remove from the fridge (if frozen, thaw in the fridge overnight), top with tater tots, and allow to warm up slightly while the oven preheats. Bake as usual.