In a bowl, stir together the salt and 3/4 Cup water until the mixture forms a slightly stiff paste resembling wet snow.
Arrange the rib roast, fat side up, in a roasting pan and coat it completely with the salt mixture, patting the mixture on about 1/4 inch thick. Roast the beef in the middle of a preheated 325°F oven for 2 hours (about 22 min per pound), or until the roast registers 130°F on a meat thermometer for medium-rare meat.
Transfer the beef to a cutting board and let it stand for 15 minutes. Remove the salt crust with a hammer before carving the meat.