Make the burger bun dough

• Warm the milk and combine with the yeast and sugar, then let it sit until foamy.
• Mix in the flour, egg and salt, then knead in the softened butter until the dough is smooth and elastic.
• Cover and let the dough rise until doubled in size.

Shape and bake the buns

• Divide the dough into equal portions and shape into smooth round buns.
• Place on a lined baking tray, cover and let them proof until puffy.
• Brush with egg yolk and bake at 180 °C until golden brown.

Make the animal-style sauce

• Stir together the mayonnaise, ketchup, yellow mustard and sweet relish until smooth.
• Chill until ready to serve.

Fry the animal-style fries

• Cut the potatoes into thin fries and rinse well, then dry thoroughly.
• Fry in hot oil until golden and crisp, then drain.
• Top the hot fries with a spoonful of the sauce, diced onion and a slice of cheese.

Cook the patties

• Form the ground beef into thin patties and season with salt and pepper.
• Sear in a hot pan, then top each patty with a slice of American cheese to melt.

Assemble the burgers

• Spread the sauce on the toasted buns.
• Layer the lettuce, tomato, pickles, patty with cheese and diced onion.
• Close the burgers and serve with the animal-style fries.