As soon as my mom tasted it, she rushed over to get the recipe from me.

ground beef, one pound
1 big finely sliced onion
eight pieces of rye bread
Four pieces of Swiss cheese
Cheddar cheese, four slices
Grilling butter
Sprinkle with salt and pepper, according to your preference.
a half cup of mayonnaise
ketchup, 2 tablespoons
a spoonful of sweet pickle mixture
1/8 spoon Sauce made with Worcestershire pepper
How to Follow
Make the secret sauce first. Mix together the Worcestershire sauce, sweet pickle relish, mayonnaise, and ketchup in a small bowl. Thoroughly combine and reserve.
Melt a tablespoon of butter in a large pan set over medium heat. After around fifteen to twenty minutes of cooking, add the cut onions and toss them regularly to make them caramelize. After taking it out of the pan, put it aside.