Brown ground beef. Brown ground beef in a skillet over medium high heat. Once meat has browned drain the grease then add beef and onions back to the skillet and cook until softened.
Add other ingredients. Add mayonnaise, mustard, ketchup, and pickle relish to the ground beef and stir to combine. Salt and pepper to taste.
Press the tater tots. After 10 minutes remove the muffin pan from the oven and use a tamper to press the tater tots down into each cup. This will create a tater tot cup.
Fill the tater tots. Fill the tater tots with the ground beef mixture and top with cheddar cheese. Place the tater tots back in the oven and cook for another 15 minutes.
Make special sauce. While the cheeseburger tots cool mix together all of the special sauce ingredients. Drizzle the special sauce over the cheeseburger tots and top with mini pickle slices.