Clean the fish inside but leave the tail and fins. Beat the egg white until fluffy, I had two medium fish, I used 3 egg whites. Once they are fluffy add the salt and mix. Add salt until you obtain a thick "paste". In an oven pan, make a thin layer with the paste, lay the fish, inside the fish put the rosemary and sage, and other herbs if you like. cover with the paste Not too thick, but make sure it's totally covered. Put in the over until the crust is golden brown. It's a bit messy once you remove the crust, but so delicious.