China Blue, the sister restaurant of Café China on E. 37th St., is in the old Capsouto Frères space, but if you’re walking down Watts from the east, you could almost miss the entrance. The main dining room is high-ceilinged and feels as much of old Soho as it does of Shanghai. Compared to most everywhere in Chinatown, China Blue has ambiance, but if you come with visions of The Last Emperor, or even more than a pinch of chinoiserie, you might be disappointed. The waiters wearing white shirts, black bow ties, and loose suspenders are a step in the right direction. (The paper napkins are not.) And China Blue is refreshingly calm, verging on placid. The menu is big, with a substantial dim sum section.