SAN FRANCISCO — On a dark corner here in the Mission District on March 31, the doors opened at 7 p.m. for an under-the-radar pop-up dinner. Stationed at the entrance was a man who meticulously carded each of the 60 guests, even two with white hair.

Inside the bar, long tables were set with wineglasses, place cards and something you don’t see much of anymore: ashtrays.

Soon after the party began, smoke wafted through the chandelier-lit room. Servers passed kimchi mini-pancakes prepared by the evening’s chef, Robin Song, of the Mission’s popular ham-and-oyster bar, Hog & Rocks.

A university professor who arrived a little late slid into his seat, saying, “You know, you can smell this place from across the street.”