On a recent Saturday, just down the street from the Lincoln Park Steps on California Street, a crowd milled about on the sidewalk. They weren’t waiting around for a photo op in front of the iconic mosaiced staircase. Instead, they had queued up to receive an order of tartes, bread, soup or some other tasty treat made by Philippe Delarue. Over the past two years, the French expat and pastry chef has built a following running a pop-up patisserie out of his Eduardian flat every weekend.