Not on the subject of food, but on the subject of Mumbai:
I’m quite interested to watch this. On the subject of food, in the trailer there is a shot of a woman mixing spicy puffed rice (we call this jhal muri in Bengal, don’t know what it is called in Maharashtra), which to me is iconic amongst the cheap snacks ubiquitous on Indian trains.
Sukkha Bhel / Dry Bhel – as compared to Bhel (Puri), this has no chutneys. Usually puffed rice (mamra / murmura), finely minced onion, green chilli, dry spices (red chilli powder always, sometimes others), and finished with lime juice and possibly a drizzle of oil. Sometimes peanuts are added.
Less messy on a train (and less work at home) than full-on bhel!
The trains – both local and long distance – are such a rich source of stories, it is surprising the subject has not been mined further before now (esp by low-hanging fruit type folks).
Mumbai local trains were part and parcel of my life since I was a kid, even though we had a car, because the speed and functionality superseded everything else. It’s the everyday observation that’s fascinating to me more than the Q&A, but I’m intrigued by the link you posted and will try to track the fil down.