Patty Melt with Secret Sauce (Print Version)

# Ingredients:

→ For the Secret Sauce

01 - 1/4 cup mayonnaise
02 - 2 tablespoons ketchup
03 - 1 tablespoon Dijon mustard
04 - 1 teaspoon pickle juice
05 - 1/4 teaspoon paprika
06 - 1/4 teaspoon garlic powder

→ For the Patty Melts

07 - 2 tablespoons olive oil
08 - 2 large onions, thinly sliced
09 - 12 ounces 85/15 lean ground beef
10 - 1/2 teaspoon salt
11 - 1/2 teaspoon black pepper
12 - 1 teaspoon Worcestershire sauce
13 - 8 slices rye bread
14 - 3 tablespoons unsalted butter, softened
15 - 4 Swiss cheese slices
16 - 4 cheddar cheese slices

# Instructions:

01 - In a small bowl, combine the mayonnaise, ketchup, mustard, pickle juice, paprika, and garlic powder. Whisk until fully blended and set aside.
02 - Heat the olive oil in a skillet over medium-low heat. Add the sliced onions. Cook for 30-40 minutes, stirring occasionally, until the onions are deeply golden brown and caramelized. If the onions start to stick, add a splash of water. In a bowl, mix together the ground beef, salt, pepper, and Worcestershire sauce. Form into four thin, oval-shaped patties. Cook the patties in the same skillet over medium heat until browned, about 2-3 minutes per side. Remove and set aside.
03 - Spread one side of each bread slice with softened butter. Layer the bottom bread slices buttered-side down with Swiss cheese, beef patty, caramelized onions, secret sauce, cheddar cheese, and top bread slice buttered-side up. Cook in batches in the skillet over medium heat until both sides are golden brown and the cheese is fully melted, about 1-2 minutes per side.
04 - Store leftover secret sauce covered in the fridge for up to 5 days.