You can’t build a sand castle with dry sand
Mix egg whites and Kosher salt to help the salt adhere to the food. The mixture binds together and cooks into a hard, custom-fit baking vessel. Use enough egg white to create "wet sand" (about 1 egg white for every 2 cups of salt).
You can add cracked spices into the salt. This creates a wonderful scent and adds flavor to the dish. When I baked duck breast, I used black pepper, coriander, and star anise.
Spread a half-inch layer of the salt mixture on the bottom of your sheet pan or casserole dish.
I played around with using salt without the egg whites. It works best on small or flat items that can simply be buried, without the risk of sand slipping off the sides. I liked how the skins of small new potatoes came out more papery with insides that were creamy and moist, just like the version I did with salt and egg white. Also, it was fun to dig around in the salt for the potatoes.
Add food and aromatics
Pat the food dry and place it over the salt bed, surrounded by aromatics.
This bronzini was cooked with lovage from my local community garden. The red snapper was stuffed with a few slices of Meyer lemon and some rosemary. You could use bay leaves, other herbs, shallots, garlic—anything to infuse the food with added flavor.
A protective layer of fat or skin helps prevent the food from absorbing too much salt. If you are cooking skinless chicken breasts, you can wrap them in cabbage leaves.
Tuck cavities closed or cover them the herbs.
Cover food completely and bake
Don't be stingy with the salt. You really need to use a lot. I used about eight cups for a two-pound snapper.
Cover the food entirely, with about a half-inch layer of salt all around it.
I use an oven temperatures between 400° and 450°F. (The snapper cooked in about 30 minutes and the bronzini in 15 minutes at 450°F. Small duck breasts took 25 minutes at 425°F. A four-pound chicken was done after about 1 hour and 15 minutes at 420°F. Potatoes took 50 minutes at 400°F.)
Inadequate coverage = uneven cooking
Here are duck breasts that didn’t get covered with enough salt. The breasts that were exposed to the air were cooked more than the ones that weren’t.
Crust becomes golden in the oven
But the crust is not the best indicator of doneness. You can push an instant read thermometer through the crust. I cooked the fish to 135°F and the duck to 125°F (higher on those unlucky exposed pieces). The whole chicken came out of the oven registering 160°F, but after a few minutes of resting inside its hot shell, it reached 165°F.
Crack the crust open
Opening up the crust is pretty exciting and just a little bit of work. The most visually appealing way to do it is to cut along the side and pry open the top of the shell in (ideally) one piece.
Dust off excess salt with a dry pastry brush and allow meat to rest.
I removed the salty skin and filleted the fish. Though I didn’t do it here, you can fillet the fish while it’s still on the salt.
Results are moist and the inherent flavor of the food shines through
I loved the way this whole chicken turned out—super moist, both the breast and the dark meat. I rubbed the chicken with a blend of smoked paprika and crumbled saffron and stuffed it with garlic cloves. Then I wrapped it in a couple of layers of cheesecloth before layering on the salt. It kept the skin from getting too salty during the long cooking period and kept salt out of the cavity. The skin was beautifully golden and red and scented with the warm spices.
If you want a tan
It usually wasn’t an issue that the meat was not browned, but if you want, you could sear it before layering on the salt.
When I first made the duck breasts, I sliced them and put them in sandwiches with watercress so the lack of browning wasn’t even visible. The next day, I had a leftover breast for a salad, and added some hard-boiled eggs. I wanted some color on the skins so I seared the skin side in a hot skillet for a couple minutes before slicing the meat.