That's actually what we need. Mix mayonnaise with sour cream and optionally salt and pepper. I didn't do it.

With tuna drain off the liquid as much as possible. I have got him quite some liquid. But nothing, the taste is not affected. Mix it in a separate plate with a small amount of mayonnaise-sour cream mixture and spread on a dish.

Take the onion, cut smaller. Further it is necessary to fill it for a few minutes with boiling water, that came out bitter. After drain the water and rinse the onion with cold water. Then do the same as with the fish, mix with mayonnaise and spread on a layer of tuna.

Eggs cut into cubes, mix with mayonnaise and spread on onions.

Apples peel, RUB on a coarse grater. If very juicy, then a little squeeze. Further actions are the same: mix with mayonnaise and spread on top of eggs. Unfortunately this layer I forgot to take a picture. The top layer of apples lubricated with the remaining mayonnaise and sour cream mixture. Sprinkle top with grated cheese. And decorate as desired ( e.g. pomegranate seeds, I have a cranberry and herbs) Put in the refrigerator for a few hours. BON APPETIT.