Look at them. How yellow and fluffy they are. These are Japanese sweet potatoes, known as ‘murasaki’, from the word for purple. I first had them in Japan last year on a ‘stove train’ in the northernmost tip of the main island. Chugging through the snow, each carriage had coal stoves at either end. A vendor rolled his trolley along the train, offering bags of dried cuttlefish to toast on the stove top and small bottles of sake.
Three middle aged Japanese women befriended me, helping me to carry my enormous blue suitcase up and down stairs. They’d brought extra snacks for the stove train: mochi cake and sweet potatoes.
I fell in love with both, but especially the small purple skinned sweet potatoes. I’m not a big fan of sweet potatoes (big, overly sweet and watery) although purported to be better for you than ordinary potatoes. These are something else: chestnutty, dense, drier, starchier.
I bought these at Natural, Natural in Finchley Road but they are also available at the Japan Centre. I baked them in their skins, and served with slices smoked trout and creme fraiche.