Mangosteen, rambutan, dragon fruit, longan, lychee — Vietnam's fruit is incredible. Buy from carts where you can see the cutting board.
Ask the vendor to peel and cut for you ('cắt giùm em'). They'll add a sprinkle of chili-salt for a sweet-savory kick that's pure street-food joy.
Avoid pre-cut fruit sitting unrefrigerated for long stretches. Whole, just-cut fruit is the safer bet for sensitive stomachs.