Preheat the oven to 450 degrees F, or preheat a wood-fired oven.
Cover the firewood with water and soak for 15 minutes. Remove and add to a large roasting pan.
Sprinkle the lamb with salt and pepper. Add enough kosher salt to a large bowl to cover both legs of lamb during roasting. Add the chile flakes, oregano, rosemary, thyme and egg whites. Mix until the mixture looks like wet sand.
Cover the logs with a layer of herb salt. Place the legs side by side on top of the salt, then cover the lamb completely with more herb salt.
Roast until the lamb reaches an internal temperature of 120 degrees F, about 1 hour.
Let rest for 15 to 20 minutes before removing the "salt cap." Slice and serve.