The science of the beautiful, weird dessert known as “raindrop cake”

The clear, dense jelly used in New York City chef Darren Wong’s “raindrop cake” may be new to Brooklyn foodies—who are lining up by the hundreds to buy it at his weekend stall—but it’s very familiar to people from Japan. Gelatinous desserts and savory foods made with agar, a substance derived from algae, have long been popular in Japan, where the unflavored jelly is used as a vehicle for other flavors—edamame milk kanten, anyone?