Animal Style Fries (in-N-Out Copycat)

Thinly slice potatoes into shoestring fries. Soak the potatoes in cold water for 30 minutes. Drain well.
Heat 2 tablespoons of oil in a large skillet over medium heat. Add the onions and cook until they start to soften, about 10 minutes. Cover and continue to cook, stirring every 5 minutes, until the onions are dark golden brown, 30 to 35 minutes more.
Heat oil to 350 degrees F. Deep fry the potatoes until they are golden and crispy. Remove the fries from the oil and place on a paper towel-lined plate to drain.
In a small bowl, mix mayonnaise, ketchup, mustard, pickles, chives, Worcestershire sauce, garlic, salt, black pepper and caramelized onion in another bowl.
To serve, place fries on a plate, season with salt and pepper, top with cheese slices. Allow the cheese to melt then top with the sauce.