"No, it tastes like burnt socks," Huaisang says, grimacing very dramatically. "Very dirty burnt socks."

Huaisang only drank it because the doctor lady gave him some and she clearly knew her business, so probably it's medicinal, but it's still horrible and he's only drinking any that the doctor lady insists on prescribing for him. Otherwise he'll just drink hot water until one day hopefully he finds some decent tea. He does not have any hope for actually finding decent tea in this frozen land of surly convicts.