Banh Mi So #1 began humbly back in 1994, selling its namesake pork-and-pickle-stuffed baguettes from a shrouded storefront on far South Grand. In twelve years it has slowly evolved intowell, a slightly sizier hole-in-the-wall. Owners Lynne and Thomas Truong still offer a smaller menu than other Vietnamese restaurants in town. But none come close to rivaling the zing and freshness of Lynne Truong's fare. Vietnamese patrons laud the place for its special fish sauce, whose recipe the Truongs safeguard as if it were a matter of national security. "We have many workers from other Vietnamese restaurants want to work here and learn the recipe," says Thomas Truong. "But they don't fool us." He's something of a chatterbox, an entertainer who putters around between tables while Lynne works her magic in the minuscule kitchen. Word has spread that the Truongs turn out matchless spring rolls. They say they now furnish hundreds of the delicacies to bars and company functions every week.