Preheat your oven to 400°F (200°C).
In a large skillet, brown the ground beef over medium heat.
Add the chopped onion to the skillet and sauté until translucent.
Stir in the Thousand Island dressing and pickles, then season with salt and pepper.
Layer the beef mixture in a greased 9x13-inch baking dish.
Sprinkle the shredded cheddar cheese evenly over the beef mixture.
Top the casserole with tater tots in an even layer.
Bake in the preheated oven for 25-30 minutes, or until the tater tots are golden brown.
Let it cool for a few minutes before serving.