Glancing at the signature offering at BLK MKT Eats(9 S. Vandeventer, 314-391-5100), you might think you're looking at a sushi roll. After all, the julienned vegetables, rice and cuts of protein are all wrapped tightly in a thin sheet of nori, just like the Japanese-inspired treat.But once you get one of these babies in your hands, you'll realize how wrong you were.…