A VAULT OF SALT
Although the quantity of salt required might seem startling at first, rest assured you can tuck a whole meal’s worth of sides around your main course. Root vegetables like onions, shallots, or potatoes will roast down to a perfectly seasoned, no-fuss side dish as they bake. Scatter veggies—skins and all—around the centerpiece, leaving at least an inch between them, before burying it all beneath its blanket of salt.
Step 1: Mix the Salt
Begin with very coarse salt; there are pebbly, extra-coarse versions in Spain, but coarse kosher works just fine. You will need about 4–5 pounds. Use your hands to mix the salt with egg whites in a large bowl until it feels like damp sand. The egg helps the salt form a hard shell during baking, making it easier to remove in large pieces. (If you feel confident, you can moisten the salt with water instead of egg whites, as the fishermen do.)
Step 2: Form the Salt Crust
Line a rimmed baking sheet or roasting pan with a piece of parchment paper, then spread around enough of the salt mixture to form a layer about half an inch thick. Gently pat it down to pack evenly. Lay the fish, meat, or whatever you are baking on top, then cover completely with enough salt to fully bury and seal the ingredients in an even layer at least ½-inch thick. Gently pat down the top layer to pack evenly.
Step 3: Bake
Carefully, without shifting the salt, transfer the pan to a hot oven (425°F). A high temperature encourages a firm shell to form quickly, ensuring no flavors or moisture can escape. The salt crust might brown slightly and begin to crack in some places. However tempting, do not pry open the shell to check for doneness. Follow recipe times closely, or estimate about 15 minutes per pound for whole fish and about 1 hour for a 2-pound roast.
Step 4: Remove the Crust
Remove the pan from the oven, and let cool just slightly. Using a heavy wooden spoon or kitchen mallet, break the hot crust into large chunks. Hot steam will escape, so pull off the pieces carefully. Sweep aside loose grains, and gently lift out the buried item. (For whole fish, it may be easier to lift out just the fillets.) Working quickly to keep the warm juices from dissolving any salt, brush away any clinging grains with a pastry brush.