Peel the eggs and egg whites separated from yolks. In a large shallow bowl cake shred egg whites and pressed by hand to form as a base. On them Grate the feta cheese, enough to cover the egg whites and also pressed. On the feta cheese in the same way Grate half butter (to make it easier is better before grating it to put in the freezer for a while). Fillets of Tuna drained from the sauce tear on a in small pieces and distributed over the butter. Sprinkle with pepper and cumin and cover with remaining grated butter. So shaped cake sprinkled with cheese on all sides and pour the mixture of mayonnaise, yogurt and mustard. Top sprinkle thickly with grated yolks. Decorate with optional pickles, carrots, peppers, olives. It is necessary to stand in refrigerator at least overnight to set.