Soki is a pork sparerib with the cartilage that's cooked for a really long time. The Japanese say that it's cooked for so long that the fat is no longer bad for you (the bad fat is cooked off) and the remaining fat is collagen, which is good for the skin. It would make sense, since most Okinawan traditional foods are local varieties--often similar, but not identical to other Japanese ones--and are unbelievably fresh.
This Soki Soba was found at an izakaya on Kokusai Dori in Naha. The noodles, while called soba, are yellow and unlike soba found in most of Japan. Okinawan soba resembles udon elsewhere and contains no buckwheat. Historically, the Japanese were rather miffed by the misnomer, but their reverence for culture and tradition allow Okinawa to keep calling it soba despite not being soba in the purist sense.
Whatever else it is, it certainly is delicious.