The day before you want to make fries, mix up all the ingredients for the special sauce in a small bowl. Cover it and put it in the fridge overnight, stirring a couple times as it chills.
The next day, preheat your oven to 400º.
Slice a large Russet potato into about 1/4" strips.
Bring a small saucepan filled about halfway with water to a rolling boil. Put the freshly sliced fries in the saucepan for 2 1/2 minutes. This is to clean out excess starch.
Place the slices on some paper towels after the 2 1/2 minutes are up and let them cool. Get a small sealable sandwich bag and put the olive oil, salt and pepper (optional) inside. Once the fries are cooled, put them in the bag and give it a good shake.
Line a baking sheet with some parchment paper. Spread the coated fries on the sheet, trying your best to make sure they don't touch. Bake them for about 30-35 minutes or until crispy and golden brown. Oven times may of course vary.
About 5 minutes before the fries are done, heat up a small pan on the stove lined with a thin coat of olive oil. Put the chopped onions in and sauté them until they are also golden brown but not completely blackened.
After the fries are done, place them on your platter of choice and cover them with the slice(s) of cheese. Put your platter in the microwave for about 30 seconds or until the cheese melts.
Take it out of the microwave and spread around the cooked onions on top. After that take your sauce out of the fridge and spread as much as you want on your platter of fries.
Stand back for a second and take in the absurd amount of awesome you just created with your own two hands before you savour the few minutes that it will take you to devour this culinary masterpiece.