DA NANG, Vietnam — Bui Van Phong faced a choice when the Vietnam War ended 50 years ago: Stay in his small village, helping his parents carry on the family's centuries-old tradition of making fish sauce, or join the hundreds of thousands of people fleeing his country for a better life.

Phong chose to stay behind and nurtured a business making the beloved condiment, known as nuoc mam in Vietnam, that is now in its fourth generation with his son, Bui Van Phu, 41, at the helm. Fish sauce from the village has been recognized by Vietnam as an indelible part of the country's heritage and the younger Bui is acutely aware of what that means.