As a gardener (and as a cook), it would be hard not to like the Vietnamese interest in vegetables and greens. Vegetables at every meal, great, and the variety of fresh herbal greens, extraordinary.
I spent some time today ordering seeds to grow some of them (this link is an excellent overview of their diversity). Most, outside of cilantro and Thai basil, aren't greens that we grow frequently in the U.S., although they're available in Southern California in farmers' markets grown by folks of Vietnamese heritage. Thanks to one of my favorite podcasts for the information!
In markets in Vietnam, we saw both diversity of greens and fruits, tropical and imported. (Imported apples and grapes are a special treat).
A traditional (and organic) vegetable village near Hoi An was one of the most attractive vegetable production areas that I've ever seen - neat mounded rows of vegetables grown in fabulous soil with freshwater 'seaweed' for fertilizer.