Spicy-Tart Split Green and Red Lentils with Coconut

As a child in India, it took me a while to fall in love with the essence of slightly astringent, primarily tart kokum. Peculiar to the Maharashtrian community in Goa and Mumbai, the dried dark purple-black skin of this tropical fruit, a close relation to mangosteen (which has nothing to do with mango), provides sour flavor to many of their curries, both vegetarian and non-vegetarian. Here a quantity of the extracted juices, added toward the end, gives the curry a sharp gusto to balance out