I TAKE A BORDERLESS approach to cooking. If an Eastern ingredient can enhance a Western dish, I'll stir it right in. Perhaps the finest example is nuoc mam—that's Vietnamese for fish sauce. Used primarily in Southeast Asia (in Thai, it's nam pla), but also in Korea, China and Japan, the red-amber liquid, extracted from salted and fermented fish, can be deployed wherever savory depth is needed.

I learned to sneak fish sauce into all kinds of fare from Mr. Lap Huynh, the Viet chef and owner of several well-regarded French restaurants in California in the 1980s and '90s. He was a business associate of my dad's, a charming, handsome man with gumption. He often swapped cooking secrets with my mother, an accomplished Vietnamese cook in her own right. On one occasion, he revealed that he sometimes added fish sauce to the food at his Au Chambertin restaurants in Palo Alto, Santa Barbara and Santa Monica.

Quelle horreur! How brazen to breach the sanctity of Franco culinary traditions. But Mr. Lap contended that fish sauce made everything from escargots to coq au vin extra tasty. He invoked dam da, the notion that foods should have a deliciousness that's practically addictive. It's the Viet equivalent of Japanese umami, a savory flavor that makes you say, "More, please."

I've kept the fish sauce trick in my back pocket ever since. When a dish needs an assist, I fix it with a splash of nuoc mam. No one is the wiser. Used judiciously, the sauce doesn't call attention to itself; you don't taste the sea because it plays a supporting role, unifying and rounding things out.

Look for fish sauce in the Asian or international section of a supermarket, at an Asian market or online. The brands Flying Lion and 3 Crabs (both made by Viet Huong), Red Boat and Megachef are all excellent. Good fish sauce shouldn't smell fishy or foul. Glass bottles tend to signal better quality. The terms nuoc mam nhi and nuoc mam cot indicate that the first extraction was used—a sign of solid craftsmanship and good flavor.