Minus the occasional spelling contest or drag-queen bingo, most bars are pretty much the same every night—Norm's at the corner, and Sam's behind the stick. But if you walk in on any Tuesday through Thursday this March at tiny 23rd Avenue basement bar space Function PDX (919 NW 23rd Ave., 971-712-3016, functionpdx.com), you'll discover the hardwood and black-vinyl place has transformed into Small Bar, where a former chef at Bamboo Sushi might serve a lovely, discrete sushi menu, or Ración star chef Anthony Cafiero may serve you the best jackfruit vegan taco you've ever tasted.

Or you may just be privy to a free Blue Star doughnut from next door, just because. The cocktail menu is a pared-down list of classics, including a truly terrific apple brandy Jack Rose. The five-deep beer menu pours Modern Times IPA or gose at a lower price than at the brewery. But don't go in Friday looking for Small Bar. On the weekend, the space morphs into a wine bar called Muselet, currently devoting the month of March to female winemakers. And if you pop in on Sunday, March 18? You'll be at a bar called Aperitif devoted to the wine cocktail.

At Function, every bar is a pop-up. Small Bar's Nick Lopez and Reichele Caviteno are doing a trial run before maybe opening in earnest at a fixed location: They took over the worst bar nights in the week as a calculated trial measure. Meanwhile, the Muselet weekends are the resurrection of a French-centric wine spot that failed in its much larger space on the South Waterfront last year. Maybe you'll never get comfortable at Function—but you can also walk into a new bar every few days without changing your seat.