For the cheeseburger: Heat some grapeseed oil in a medium saute pan over medium heat. Add the onion and cook until caramelized, 15 minutes. Hold.
Heat a skillet over medium-high heat. Form the beef into a patty and sprinkle with salt and pepper. Sear the burger in a hot skillet; cook to the desired temperature. Add the cheese when ready.
In a small bowl, mix the ketchup, mayonnaise, mustard, garlic salt and onion salt. Hold until ready.
Toast the burger bun. Place the bun on the plate; spread on both sides with the sauce. Layer the bottom bun with the lettuce, tomato and pickles. Top with the burger and the caramelized onions. Cover with the bun top and serve.