American Cheeseburger

Finely chop the white onion. Wash and dry the parsley, remove the leaves, and finely chop them as well. Slice the red onion into thin rings and set aside. For the sauce, whisk together 1 tsp mustard, vinegar, egg yolk, salt, and pepper. Gradually add 8 tbsp sunflower oil while stirring continuously. Then stir in half of the chopped onion and half of the chopped parsley.

Now thoroughly knead the ground beef with 1 tbsp mustard, breadcrumbs, salt, pepper, and the remaining half of the diced onion, then shape into 4 patties. Heat 2 tbsp sunflower oil in a pan and fry the patties for 8 to 10 minutes, turning regularly.

Wash and dry the lettuce. Wash the tomatoes as well and cut them into slices. Cut the burger buns horizontally and toast them. Place the romaine lettuce on the bottom toasted burger bun. Layer the patty on top of it. Place a slice of Gouda on the patty. Next, arrange the ketchup and red onion rings together with the mixed sauce. Place the tomato slice on top and finish with the upper half of the bun.