A thick brown crust, a moist interior and an aroma that tempts the palate -- these sound like the qualities of any well-roasted cut of meat, but guess again: They're what you get from baking potatoes in a seasoned salt crust. Salt crusts insulate the potatoes as they cook, trapping steam inside. On the outside, salt draws moisture from the skin, dehydrating and crisping it as it bakes. Only coarse kosher or sea salt will do. Adventurous cooks should try mixing a specialty salt, such as Himalayan pink or cedar-smoked, with the kosher or sea salt to give the crust an elegant edge.
Seasoning the Salt
Seasoning salt isn't something you do every day -- if done superfluously, it can lead to overkill in a dish -- but when you use spices the right way, it's a thoughtful, elegant method of incorporating fragrance and aroma. Simply combine the herbs and spices with the salt until evenly distributed. Go big; go floral; go aromatic with your choices: Peppercorns, rosemary, sage, thyme and fennel -- fresh and whole, not dried and crushed -- infuse a salt crust masterfully. You need about 1/2 to 1 cup of salt per potato, depending on its size.
Selecting the Spuds
Use high-quality potatoes -- free of blemishes, soft spots and growths, and with the skins intact. A few small eyes you can scoop out, but anything more and you should get something fresher. Don't limit yourself to Russets -- the king of baking potatoes -- even though they're awesome "bakers" in their own right. Medium-starch potatoes, such as Yellow Finns, new potatoes -- red, white and purple varieties -- and mature reds develop a creamy interior during baking in the salt crust, almost as if they were whipped with cream. Scrub the potatoes and let them dry for about an hour.
Coating the Crust
Heat the oven to 350 degrees Fahrenheit. Coat the potatoes with a thin layer of olive oil. Mix the salt with just enough egg whites to feel like wet sand, or about 1 tablespoon of white for every 2 cups. Next, spread a 1/2-inch layer of moist salt in a casserole or shallow baking dish and lay the potatoes in it, pressing down slightly on each. Finally, pack the salt around and over the potatoes, encasing each in a 1/2-inch-thick layer.
Baking the Bakers
Baking time varies with the size of the potato: Small, new potatoes should be ready in about half an hour; medium to large potatoes take about 1 hour. To test, slide a paring knife through the crust of one of the largest potatoes and into its center. If, after you crack the crust, the knife slides in and out of the potato with ease, they're good to go.
Serving the Spuds
Serve the potatoes straight from the dish, or use a spoon to crack the crust in the pan around each. After cracking the crust, lift each potato -- carefully, so as to keep its crust intact -- from the dish using the spoon, and transfer it to the serving plate. From here, the guests need simply crack the crust and separate it from the potatoes.