At a food fair in New Delhi, a vegetable exporter from the Philippines set out its wares: bags of dried moringa and lemongrass, bundles of taro leaves and a bowl of laing, the creamy coconut-milk stew made from them. The question Dry Tech Manufacturing wanted to answer was simple: could the simple Filipino food it sells under its Sheentaro brand tantalise the taste buds of the world’s most populous country? India has hundreds of millions of vegetarians, more than any other country on Earth,...