Prepare the Onions: Peel and slice the yellow onion into four 1/2-inch slices. Drizzle with olive oil and season lightly with salt, pepper, and a pinch of sugar. In a pan on medium-low heat, cook the onion slices for 10 minutes on each side until they are seared on the outside and soft in the middle. Set aside for assembly.
Prepare the Beef Patties: Roll 3 oz balls of ground beef and smash them into thin patties. Season with salt, pepper, and garlic powder. Heat a pan or griddle with 1 tablespoon of olive oil on medium-high heat and sear the patties for 2 minutes per side or until fully cooked. Add a slice of American cheese to each patty, let it melt, and then remove them from the pan.
Assemble the Burger: Place one cooked onion slice as the base. Stack two beef patties with melted cheese on top, add a spoonful of burger sauce, and finish with another onion slice as the top.
Make the Burger Sauce: In a bowl, combine mayonnaise, ketchup, yellow mustard, relish, white sugar, apple cider vinegar, and Worcestershire sauce. Whisk until smooth, then spoon it over the burger or serve it on the side for dipping.
Enjoy: These steps ensure a flavorful, perfectly cooked Onion-Wrapped Flying Dutchman Burger that’s as delicious as it is satisfying!