Preheat oven to 450 degrees fahrenheit. Zest and slice 2 of the lemons into rounds, and cut the other 2 into wedges for serving.
4 small lemons
Whip egg white until frothy, either with a mixer or by hand with a whisk. Transfer whipped egg white to a large bowl and combine with kosher salt, lemon zest and 2 tablespoons chopped fresh parsley. Using your hands, if needed, to mix until the mixture feels like wet sand.
Rinse fish thoroughly with cold water and pat dry with paper towels. Choose a large rimmed baking sheet, roasting pan or casserole dish large enough to fit your fish with plenty of space. Place enough salt mixture on the bottom of the baking sheet to cover a space roughly the size and shape of the fish with about 1” of space around it and ½” deep. Place a few lemon slices and a sprinkle of fresh herbs on the salt, then top with the fish. Tuck remaining lemon slices and fresh herbs inside the cavity of the fish. Top fish with remaining salt mixture.
3 pound fish, 2 sprigs dill
Pat with your hands to form a smooth, sealed mound, keeping fish and tail exposed or covering completely with salt.
Using a spoon, create a few rows of "scales" on the fish body. If head and tail are covered, create tail lines with the handle of the spoon and use your finger to make an indent for the eyeball (optional).
Place in oven and roast for 15 minutes or until it reaches 140 degrees.
Remove and allow the salt crusted fish to rest 5 minutes.
Crack and remove crust at the table before serving. Or serve each fish individually and allow guests to crack with their own mallets. Once top layer of salt is removed, peel away skin, remove bones and serve.