Adapted from Mario Batali: Molto Italiano: 327 Simple Italian Recipes to Cook at Home
Step 1: Preheat the oven to 425 degrees F.
Step 2: Pour the sea salt into a large bowl, add the egg whites, and mix vigorously until all the grains of sea salt are coated with egg whites. Spread 1/3 of the salt mixture over the bottom of a large rectangular or oval oven dish big enough to hold the whole fish. Place the fish on top.
Step 3: Cover it completely with the rest of the salt. No part of the fish should remain uncovered.
Step 4: Place the dish in the oven, reduce the heat to 400 degrees F, and cook for 30 to 40 minutes, depending on the thickness of the fish; generally, cook for 10 minutes for every inch of thickness at the widest part of the fish.
Step 5: Remove the fish from the oven. Crack the crust at the table with the handle of a knife or a small hammer.
Step 6: Serve with lemon wedges and drizzled with olive oil.