Swati Snacks
A kilometer or two from Colaba Causeway lies Swati Snacks, a Mumbai stalwart and a great place to try the city's street food in clean, air-conditioned, somewhat canteen-style environs. Most popular are its chaat dishes (a smorgasbord of crunchy, creamy, spicy, sweet dishes), but you can venture further afield by ordering homely Gujarati fare from under the traditional specialities section of the menu.
If you find the time, try the original Swati Snacks in Tardeo.