Salt-bake

To salt-bake is to bury food in a thick crust of coarse salt, often mixed with egg white or water, and bake it. The crust sets hard in the oven and seals the food inside, where it cooks gently in its own moisture. You crack the crust open at the table. It is used for whole fish such as sea bass and bream, whole chicken, beef tenderloin, and root vegetables such as celeriac, potatoes and beets (beetroot in the UK).

How to do it

1. Heat the oven to 200°C (400°F).
2. Mix coarse salt with egg whites, about 2 to 3 whites per 1 kg (2¼ lb) of salt, or a splash of water, until it feels like damp sand. A whole fish of 1 kg (2¼ lb) needs about 1.5 to 2 kg (3¼ to 4½ lb) of salt.
3. Spread a 1 cm (½ inch) layer of salt on a baking sheet.
4. Lay the food on top. For fish, leave it whole, gutted and scaled, with herbs or lemon in the cavity.
5. Pack the rest of the salt over it so it is fully covered, with no gaps.
6. Bake. A 1 kg (2¼ lb) fish takes about 25 to 30 minutes. Whole beets or celeriac take 1 to 2 hours.
7. Rest 5 minutes, crack the crust with the back of a heavy spoon, and lift it away. Brush off loose salt.

How to tell it is done

Push a thermometer through the crust into the thickest part. Fish is done at about 55 to 60°C (130 to 140°F) for moist flesh, or 63°C (145°F) to meet USDA guidance. Vegetables are done when a skewer slides in easily.

Why it works

The crust works like a sealed oven inside the oven. Moisture cannot escape, so the food steams in its own juices, much like cooking en papillote. The skin keeps most of the salt out, so the flesh is seasoned but not salty.

Common mistakes

• Using fine table salt. It packs too tightly and seasons too much. Use coarse or kosher salt.
• Filleted or skinned food. Without skin, the salt gets in. Salt-bake whole, skin-on pieces.
• Gaps in the crust. Steam escapes and the food dries.
• Serving the skin. On fish, peel it away with the salt.