Beat 12 egg whites together to stiff peaks in a large mixer. Gradually add the salt until all absorbed. This can be done in two parts if you can’t fit this quantity into your domestic mixer. The egg whites and the salt should be like a ball of snow.
Open the cavity of the fish and put in assorted herbs with some sliced lemon. Wrap up the fish in baking paper.
Spoon a layer of the egg and salt mixture on the bottom of a baking tray. Place the wrapped up fish on top and cover evenly with the remaining mixture.
Cook it in the oven at 220 degrees celsius for half an hour. Rest for half an hour, then carefully remove the crust and eat with a salad and mayonnaise. You can also add some trout eggs.