Sweet potato ginger soup
Cheap, warming and ready in under an hour, this is the tong sui Hong Kong families make at home on cold, damp winter nights, ladled out after dinner or before bed rather than ordered in a shop. Chunks of orange, yellow or purple sweet potato turn tender and fudgy in a clear amber syrup made with brown slab sugar and plenty of smashed ginger, so each spoonful is sweet first and then pleasantly hot. Some cooks add a few pitted red dates or a piece of dried tangerine peel. Boiling the sweet potatoes from the start is the usual slip; by the time the ginger has given up its heat, they've collapsed and clouded the syrup. Chef's tip: soak the cut sweet potato in cold water for 10 minutes to rinse off surface starch, and add it only once the ginger broth has simmered for a good 10 minutes.

































