Hanoi, Nov. 8 -- Though he speaks only limited Vietnamese and has visited the country just once, Vietnamese-American Hieu Le has opened a Vietnamese restaurant and makes fish sauce from sardines in Colombia.

Hieu Le's restaurant in Medellin, Colombia, is called District 1. Beneath its name is the Spanish phrase "Autentica Cocina Vietnamita", meaning authentic Vietnamese cuisine. Paper umbrellas hang outside, while red lanterns cast a warm glow over dark wooden tables inside. Paintings of a woman wearing an ao dai and a conical hat, alongside illustrations of Vietnamese dishes such as broken rice, crab noodle soup and banh mi, decorate the walls.

At a nearby table, Daniela, a 23-year-old Colombian woman, leans over a bowl of the restaura...