finely chop the onion and fry in a small amount of vegetable oil with mushrooms. cool down.
walnuts chop or grind not very large, but not in the dust. we collect the salad in layers.
1) ham, smear with mayonnaise
2) mushrooms with onions
3) egg, grease with mayonnaise
4) walnut
5) cheese, grated on a fine grater