Grind the pork, onions, and potatoes using a meat grinder. Add 3 eggs and mix well.
Add salt and ground black pepper. Mix thoroughly, then refrigerate for 30 minutes.
Boil 7-9 eggs for 10-12 minutes until hard-boiled. Peel and chop finely.
Wash green onions and chop finely.
Mix the chopped eggs, green onions, and mayonnaise together.
Preheat the oven to 200-220°C (390-425°F).
Line a baking sheet with baking paper and lightly brush with vegetable oil.
Take approximately 1 tablespoon (about 60 g) of the meat mixture. Form it into a ball, then flatten it into a patty. Place a teaspoon of the egg filling on the patty. Fold the edges over to seal, forming a cutlet shape.
Arrange the prepared zrazy on the baking sheet close together.
Bake at 200-220°C (390-425°F) for 10-15 minutes. Remove from the oven, flip each zrazy, and bake for another 10-15 minutes.