Loved this! Came across this shop at Suntec City that sells steamed buns with various skins and fillings. Love purple sweet potato so I really enjoyed this! Bun to filling ration was just right. The mantou is supposedly flavoured (here it is spinach and charcoal) but you won't be able to taste it hah. Makes for a colourful bun though, and I think that was the whole point.