the oven to 375°. In a large skillet, heat 1/4 cup of the oil until
shimmering. Add the lamb and cook over moderately high heat, turning
occasionally, until browned, 8 minutes. Transfer to a medium baking
dish. Season with pepper; let stand for 10 minutes.
in a medium bowl, combine the 5 cups of kosher salt with the thyme,
rosemary and lavender. Add the egg whites and stir until the salt is
the salt all over the lamb in the baking dish, leaving no cracks. Roast
in the center of the oven for about 50 minutes, until an instant-read
thermometer inserted (through the crust) in the roast registers 120°
for medium-rare. Let the lamb rest for 10 minutes, then crack the crust
and remove it.
in a large skillet, heat the remaining 1/2 cup of oil. Add the
potatoes, season lightly with salt and cook over moderate heat, turning
occasionally, until thoroughly softened but not browned, about 8
minutes. Using a slotted spoon, transfer the potatoes to a platter;
season with pepper.