Bottles of pungent fish sauce are fixtures in many Southeast Asian restaurants, where it fortifies dipping sauces and adds deep savory notes to soup.

Now, the condiment is crossing the East-West divide.

"My mom used Mrs. Dash in everything," comments Anthony Strong, the nuoc mam-obsessed chef of Locanda. "I use fish sauce the same way. It's gotten to be a joke in the kitchen."

Locanda's kitchen sparingly uses pricey colatura di alici, made on the Amalfi Coast, to finish many dishes. But Vietnamese-made Red Boat Fish Sauce is splashed around liberally. It's a key ingredient in most braised meat dishes, including the rabbit sugo ($17), and in a vinaigrette Strong concedes he uses "on just about everything else."

Fifth Floor's David Bazirgan also turns to Red Boat, which is made on the island of Phu Quoc, Vietnam, adding it to duck meatballs that accompany a Thai-inspired lacquered duck breast ($29).

The Vietnamese caramel corn ($3) at Kitchenette SF, studded with peanuts and gently spiced with jalapeño chiles, gets its musky savor from a hit of the salted anchovy condiment.

Fish sauce: not just for noodle joints.