Rinse the fish when cold, dry with kitchen roll and cut into 3×4 cm pieces. Place them in a sufficiently large bowl, sprinkle with the juice of one lemon, grind a little pepper on top. Cover and put in a cool place. Remove about 16 large leaves from the cabbage and rinse thoroughly. Remove hard ribs.
Fold each savoy cabbage leaf over the filling on the side. Next, fold the other two sides over to form small, closed parcels. Tie these together with spaghetti. Arrange on a platter.
Preparation at the table:
Heat the hot stone. Pour a little oil on it and roast the savoy cabbage parcels for about 5 minutes on one side, then turn them to the other side and roast them for another 5 minutes.