This classic Indian curry, called aloo matar, balances the sweetness of tomatoes and green peas with pungent aromatics and warm spices, all tempered by the mild flavor and starchiness of potatoes. The peas usually are drab army green from the acidity of the tomatoes; we add them at the end so they retain their bright color. The cilantro also is added at the end, so to save time, prep it while the curry rests for 10 minutes. Serve with basmati rice and cooling plain whole-milk yogurt, if desired.