Pour the warm liquid (milk mixed with water) into a deep bowl, add the yeast, sugar, salt, vanillin, melted butter, half the beaten egg and the smooth cottage cheese. Mix well.

Sift in the flour in batches, adding the vegetable oil at the very end. Knead the dough, gather it into a ball and set it in a warm spot for 1-1.5 hours.

Divide the dough into pieces (you should get 5 buns of 100 g each), shape into balls, place on a baking tray and let proof for 30 minutes.

Brush the buns with the remaining beaten egg, sprinkle with sesame seeds and bake for 25-30 minutes at 180°C. Let the finished buns cool.

Cut a bun in half and toast it lightly on a grill pan. Spread mustard on top, ketchup on the bottom.

On the bottom half, place finely chopped sweet onion, a hot chopped patty, a slice of cheese and fresh lettuce. Cover with the top and serve.