A really good clone recipe for the famous Double Double Animal Style Burger from In n Out.
Please see video
1) In a small bowl, add mayonnaise, sweet relish, tomato ketchup, white distilled vinegar, sugar and mix it well to make burger spread.
2) Take a sauté pan and heat oil in it. Add onion and caramelize it. Keep aside.
3) Take two burger patties and season them with kosher salt and black pepper.
4) Put them on the grill and spread mustard sauce generously. When done turn them over.
5) Place cheese slices on each patties and let it cook and cheese melt.
6) As the cheese melts, remove the patties from heat.
7) Brush some cooking oil on the grill and toast the buns.
8) Then, spread the sauce mix on the buns, place pickle, tomato slice, lettuce, patties, caramelized onion and the second patties.
9) Wrap the burger in a butter paper and serve with spread or sauce of your choice.