Most places outside the fast-food realm serve hamburgers as an adjunct or an afterthought, but as its name implies, Burger Joint is all about burgers. It's inevitable that such laserlike culinary concentration would result in a highly refined example of the burger-flipper's art, and such is the case here. They start with organic Niman-Schell beef, form it into patties slender enough to allow appreciation of its subtle flavors yet thick enough to satisfy the carnivore within, and broil it over flames hot enough to sear and contain all of its tasty juices. The result is a hamburger remarkably reminiscent of a good porterhouse. The atmosphere is all retro-Jetsons -- aqua and lime-green accents abound. The Double Rainbow shakes and soufflélike fries are exemplary accompaniments.