Mix mashed potato well with salt and spices.
Place puris on a plate, making a small opening on the top of each puri big enough to add potato filling. Be careful to not break/crush puris as they can be fairly delicate to handle.
Fill each puri with a little bit of potato mixture, about 1-2 tsp of yogurt, and a touch of tamarind chutney. Drizzle leftover yogurt and chutney over the stuffed puris, and garnish with coriander leaves and sev.