Rinse the fish under running water and remove scales. Wash and peel the potatoes. Peel the onion.
Rub the cleaned carp with lemon juice and set aside to marinate a little. In a deep bowl, mix flour, dried dill, Vegeta seasoning and vegetable oil and knead the dough with the consistency of liquid sour cream. Cut the onions into thin rings and grate them on a coarse grater.
Grease a baking dish with oil and then pour half the seasoned batter on top. Place the onion rings on top of the dough, trying not to leave any gaps. Next comes a layer of lemon slices. In a small container, mix sour cream and vegetable oil in a ratio of 1:3 and coat the carp with the resulting mixture, which is then placed on a bed of lemons. Top the fish with the remaining batter and place a layer of potato slices.
Preheat the oven to 180 degrees and bake the fish for 20-30 minutes, then remove the baking sheet from the oven, sprinkle cheese on top of the potatoes and bake for another 10 minutes. The finished kappa should be allowed to stand for a while immediately after removal from the oven, and then it can be divided into portions.
Serve the finished carp with lemon on a large common platter or on individual serving plates. The serving can be decorated with sliced fresh vegetables and herbs, as well as lemon slices.