01 -
Bake the frozen fries on a sheet pan, following the directions on the packaging.
02 -
Mix mayo, ketchup, mustard, relish, white vinegar, salt, and pepper in a medium bowl. Cover and let it chill for a while so the flavors come together.
03 -
In a skillet over medium to high heat, melt butter. Toss in the chopped onion, sprinkle with salt, and cook for about 10 minutes, stirring until they turn golden.
04 -
After baking the fries, turn off the oven. Lay the American cheese slices over the fries, letting them sit in the warm oven for around 5 minutes until melted.
05 -
Spread the golden onions over your cheesy fries.
06 -
Drizzle the chilled sauce on top of the fries and dig in!