From dal to samosas, paneer to vindaloo, dosa to naan, Indian food is diverse and wide-ranging--unsurprising when you consider India's incredible range of climates, languages, religions, tribes, and customs. Its cuisine differs from north to south, yet what is it that makes Indian food recognizably Indian, and how did it get that way? To answer those questions, Colleen Taylor Sen examines the diet of the Indian subcontinent for thousands of years,...