I've heard of Vietnamese restaurants renaming bún as "fideo" and goi cuon as "taquitos" to get Mexican clienteles inside their doors. I've heard Mexican restaurants rename their fideo as pho and burritos as goi cuon to get Mexicans in. Then you have Dos Chinos, who mashes the two cuisines into glorious luxe lonchera desmadre.
But a restaurant that served Mexican AND Vietnamese food, with no fusion but rather cohabitation? I think there was one in SanTana years ago, but OC consumers tend to like their Mexican and Vietnamese food separately. But that just might change with the opening of Viet-Mex, a restaurant about to open up shop on the corner of Harbor Boulevard and Lampson Avenue in Garden Grove.
No other clues exist, and I personally haven't swung by to look for a menu. But by the banner, it looks like there'll be pho and pozole, side by side. Will there be bánh mì and tortas? Goi cuon and small burritos? Carne asada alongside bó luc lac? Al pastor mixed with xá xiu? One can only dream…