Cut the length of the fish belly to remove the entrails (there is no need to scale the fish since you will have to remove the skin before serving).
Carefully mix together the coarse salt, egg whites, thyme, and pepper until the mixture is thoroughly blended.
Spread the enameled baking tray with a layer of coarse salt. Arrange the fish (upsidedown) on the layer of salt, well apart from each other. Cover the fish completely with the remaining salt. Use your hands to spread the salt evenly
(30’)* Select on the display the program “Perch fish”: the ideal temperature and cooking time will appear automatically on the display.
Wait for the oven to pre-heat: the display will show you the oven temperature.
Place the tray on second shelf from the bottom of the oven. Remove from the oven and let stand for a moment. Break the salt crust and remove from the fish and discard. Serve the fillets au naturel with lemon juice or béchamel sauce prepared separately