We had a couple of notable lunches in Saigon. The first was at Quan An Ngon. The owner of this establishment found the best street food vendors in Saigon, offered them a steady wage, and brought them all under one roof to form a restaurant[1]. When you arrive (and after waiting for 10 minutes or more at this busy place) and are shown to your table, you pass the various cooks preparing their street specialties. The waiter was super-quick in taking our order so we didn't get too good of a look at the menu, but we managed to have an excellent lunch.
A couple of days later, we checked out La Fenetre Soleil (the link is in Japanese, but the photos are good). As you probably know, France ruled Vietnam for about 100 years and the influence can be seen in several aspects of life there. La Fenetre Soleil feels quite French (circa 1940), mostly due to the architecture of the building and the deliberate styling of the proprietors. There are a few tables, but we sat in two ridiculously comfortable stuffed chairs and lunched on banh mi with cold drinks. A very cool place to chill out and have a small meal or a drink...comfortable enough to lounge for hours.
[1] A great idea, BTW. I wonder if such a thing could work in NYC?[2]
[2] Or some other city somewhere else. I live in NYC so I spend a lot of time (publicly and privately) wondering if things I notice elsewhere could work where I live.