Firstly, Saute onion on a couple of tbsp of oil on medium heat in a large skillet.
Once glossy, add ground beef and cook.
Mix in the seasoning and tomato and simmer for a minute.
Add tomato sauce, beans, and corn and bring to simmer.
Mix in the sliced tortillas.
Top with the cheese, place under the broiler until the cheese has melted, about 2-3 minutes, before topping with sour cream, green onions, and avocado and enjoying!