Make the Comeback sauce by placing all the ingredients in a bowl and stir well to combine. Taste and adjust seasoning as desired. Cover and store in fridge for up to 4 days. Can be made 4 days ahead.

Place the bacon t in a large cast-iron skillet over medium-high heat. Cook for 2 minutes per side or until cooked to your liking. Remove the bacon and set aside, while leaving the drippings in the skillet. Add the onions to the skillet and cook until the onions are soft and golden brown, about 7 minutes. Season with 1/4 teaspoon salt, then remove from the pan.

Meanwhile, place the ground beef in a mixing bowl and sprinkle it with the fish sauce (if using). Using your hands, mix the meat and fish sauce together to evenly distribute the sauce, then form the meat into four ¾-inch-thick patties. Season the outsides of the patties with the remaining salt.

Fry the burgers on both sides in the skillet over medium-high heat until cooked to your desired doneness. Remove from the pan and set aside. Crack 4 eggs into the skillet and season with 1/4 teaspoon salt. Cook until whites are cooked and yolks are soft. Remove from pan.

Place the burgers on a serving platter. Top with fried onions, bacon and a fried egg! Make it a double stack if desired! These burgers are best served fresh.