Preheat the oven to 350 degrees F.
In a large skillet, fry onion in oil until translucent.
Add ground meat to the skillet and cook over medium high heat until done.
Grease the baking dish with non-stick cooking spray.
Combine the meat mixture, soup, and half of the cheese, in the bottom of the dish.
Layer tater tots on the filling.
Top with remaining shredded cheese.
Bake at 350 for 40-45 minutes.
Broil at the end for 5 more minutes to melt the cheese and toast the tater tots to a nice golden brown.
Top with green onions before serving.