Caramelize the onions

• Heat the olive oil in a frying pan and add the sliced onion with the salt and black pepper.
• Cook slowly over low heat, stirring occasionally, until soft and deeply browned.
• Deglaze with the soy sauce and cook a minute more, then set aside.

Make the burger sauce

• Mix the mayonnaise, ketchup, yellow mustard, chopped pickles, paprika and garlic powder in a bowl.
• Season with salt to taste and set aside.

Smash the patties

• Divide the ground beef into balls and place them in a very hot pan.
• Smash each ball flat with a spatula and season with salt and pepper.
• Flip when the edges are crisp and top with the cheddar slices to melt.

Toast the buns

• Toast the split buns cut-side down in the pan until golden.

Assemble the burgers

• Spread the burger sauce on the buns.
• Add the patties with melted cheese, the caramelized onions and extra pickles.
• Close the burgers and serve immediately.