Make the secret spread: Mix together the mayonnaise, ketchup, dill pickles, yellow mustard, salt, pepper, sugar, and apple cider vinegar.
Make the Animal Style Fries: Add oil and diced onions to a sauté pan set over medium-high heat. Cook, stirring occasionally, until deeply caramelized.
Add slices of cheese directly over hot french fries, and top with caramelized onions and a squeeze of the secret sauce.