Melty Burger Special (Print Version)

# Ingredients:

01 - 1 large onion, sliced thinly.
02 - 450g ground beef.
03 - 4 slices cheddar cheese.
04 - 4 slices Swiss cheese.
05 - 8 slices rye bread.
06 - 120g mayo.
07 - Salt and pepper.
08 - A bit of butter for cooking.
09 - 1 teaspoon Worcestershire sauce.
10 - 1 tablespoon pickle relish.
11 - 2 tablespoons ketchup.

# Instructions:

01 - Stir together mayo, ketchup, relish, and Worcestershire sauce in a bowl.
02 - Heat butter and cook onions until they caramelize, about 15-20 minutes.
03 - Season the meat and shape it into 4 thin patties.
04 - Cook patties for 3-4 minutes per side.
05 - Spread butter on the bread, then layer the cheese, meat, and onions.
06 - Toast sandwiches on both sides for 2-3 minutes to melt the cheese.

# Notes:

01 - Let sandwiches rest for 1 minute before cutting and eating.
02 - Serve the sauce either on the side or directly on the sandwiches.