Dharavi - the heart of Mumbai - is one of the world's largest and busiest slums, and its street food runs through its veins. Our vendors show us how to cut it in this competitive slum and make a living from its thriving inner-slum economy. Malai, an idliwalla from Tamil Nadu shares his secrets for perfect fluffy steamed rice cakes called idlis, crunchy lentil fritters called vada, all served with his trademark tomato chutney.