Oh, Shaanxi Gourmet had biang biang mian. First place that I had it in the SGV. I can’t find the old LA Weekly article that was specifically on the biang biang mian there, but there are other references to it in other articles on Shaanxi Gourmet.
EDIT: Ah, here it is Biáng Biáng Noodles + Where to Find Them - LA Weekly
Unfortunately, the photos no longer appear.