Mince the onion and microwave it in a heatproof container covered with plastic wrap for 1 minute at 600W. Let it cool. Shred the cabbage.

In a bowl, soak breadcrumbs in milk. Add ground meat, onion, beaten egg, salt, and pepper. Mix until sticky. Divide into 4 portions.

Fold each slice of cheese into quarters and roll into a ball. Place the cheese in the center of the meat portions and wrap it completely. Coat each with flour, beaten egg, and breadcrumbs in order.

Heat salad oil in a pot to 170°C. Fry the coated meat until golden brown, flipping occasionally to cook evenly.