I agree that there's a lot of value in traveling beyond the beaten tourist path, especially with the bit that this path tends to have a certain sameness to it, regardless of where you actually are. However I disagree with going out of your way to avoid it. Writing off entire cities because they're big or popular is needlessly contrarian. If you're seeking the lived experience of locals, why not go visit the NYC-equivalent of their country?
Also can't help but point out your characterization of Hanoi as the Indianapolis of Vietnam is ridiculous. Perhaps in comparative size, but Hanoi is the old capital of Northern Vietnam, and remains a fascinating vestige of what "old" Vietnam was like. No offense, but Indianapolis is Indianapolis.
I don't write off entire cities. I do make choices with limited time. As I write,
"That doesn’t mean entirely ignoring places like NYC, Istanbul, Seoul, or Tokyo. Some cities are so important they can’t be missed, and every city is a confederation of very different neighborhoods. NYC is as much Dyker Heights as it is Upper East Side.
That makes where you stay in a city more important than the city itself. "
I wasn't attempting to suggest Hanoi is the Indianapolis of Vietnam. I was Just using a stretched example to go to the less obvious place. Maybe I'm wrong, but the vibes I got here in my world is Hanoi is the less obvious place compared to Saigon.
Less obvious place would be Ninh Binh (my favorite place and experience from visiting Vietnam), not the first/second most famous place in Vietnam everyone knows (Hanoi/Saigon), or at least go for Danang, Hue, Hoi An, Nha Trang and all of these are on tourist trail anyway.
I like your style. Hanoi is a major tourist city, so I think you are really missing your stated goal because locals are familiar with tourists and the wants of tourists. Your desire for a cafe or bar says something? In my experience most cities in the world have a sameness that makes it easy to plug yourself in.
In my own country (New Zealand) when travelling I try to find places that are small (less than a few thousand population), perhaps without any accomodation (a sign of being a tourist destination). One great advantage of going to small towns overseas is that they are safe. Tourist cities are the most unsafe places I have travelled to (I particularly had unsafe situations in Rio and Nha Trang).
Perhaps apply your restaurant thinking, but just go a lot lot further down that path?
In many countries, I have felt like a millionaire, because the difference in income and situation is so profound. In Vietnam I remember talking with someone who’s monthly salary was USD50. I have met many people who had a disposable income of a few dollars a month. USD50 is less than my daily budget which is pure disposable money and is relatively obscene wealth (cost of flights alone exceeded USD50 per day: flights are expensive from New Zealand). I was just tooling around, like some sort of rich playboy, with no cares because I had been given everything by my country. I also remember how small many people were, because their food intake was limited by their means. I have very little capacity to relate, because I have never been in similar shoes (I do remember being astonished at the casual wealth of some Japanese and Americans when I was younger, but I haven’t lacked for anything in my life so it is entirely different).
I notice the same dynamic at home: my income as a software dev is radically different from many people I know. My disposable income is ridiculous: one acquaintance worked 40hours a week and was left with $20 to spend on themselves after expenses. I struggle to relate with a profit of 50 cents per hour.
Also can't help but point out your characterization of Hanoi as the Indianapolis of Vietnam is ridiculous. Perhaps in comparative size, but Hanoi is the old capital of Northern Vietnam, and remains a fascinating vestige of what "old" Vietnam was like. No offense, but Indianapolis is Indianapolis.