In a converted warehouse in the light-industrial area of Byculla on the eastern seaboard of Mumbai, India, chef Shannen Alexandra pulls a tray of mantou, or milk buns, from a rack of baked goods. Her ponytail bobs as she excitedly explains how she tweaks the classic Chinese recipe to create her buns, which, rather than the typical round shape, resemble bow ties. Her mantou differ in other ways, too. The classic version is usually made from simple milk bread, which is then steamed or fried;...