A couple of related strays
红薯 (Mand hóng shǔ; Cant: hung4 syu4).
Red potato.
These are very popular, especially at this time of year and through the winter. They are often steamed with other root vegetables. Alternatively, there are dozens of guys like this, selling them roasted in the streets.
Then we have these.
Known as 黑薯 (Mand hēi shǔ; Cant: hak1 syu4), meaning 'black potatoes' or, perhaps more accurately, 紫薯 (Mand zǐ shǔ; Cant: zi2 syu4), 'purple potatoes'. The skin can be purplish black, but the flesh is this bright purple, which fades when they are cooked.
They are used in the same manner as the red potatoes.
