Clear-Steamed Crab with Ginger

According to the ancient Chinese scheme of things that assigns qualities of yin and yang to every member of the food world, crab is considered highly yin, that is, chill-inducing. At the crab-eating parties, which abound in classic Chinese novels (hardly anything in literary China happened in the absence of food), young ladies with colds are banned from the feasting, while old grannies don shawls as the crab is set before them. Ground thistle roots are recommended as the appropriate antidot