Part of the fun of eating at a pop-up is the thrill of invading a space after hours, like being locked in the museum at night with the whale and the diamonds. Another part is the sense of being in on a secret, eating at some place that doesn’t have a Yelp entry and may not even have a name, while your friends are waiting in line at Roberta’s.

The mismatch between the borrowed space and the borrowers can send off sparks, too. Three years ago, when the Danish chef Bo Bech staged a one-night pop-up in the kitchen at Cosme in Manhattan, using ingredients he’d bought from farmers and shellfishers in Virginia the day before, his Mid-Atlantic-Nordic cooking stood out against the aromas of griddled masa and roasted chiles.

When a pop-up settles down into a space of its own, it loses those things. In their place, it takes on the extra weight of proprietorship. The owners have to make decisions that were previously made for them, and those decisions will start to define them. It’s their paint color on the wall, their scented candles in the bathroom, their name on the door.

This is the position in which we find the former pop-up Oxalis and its chef, Nico Russell, a veteran of Daniel, in New York, and Mirazur, on the French Riviera. Beginning in 2016, Mr. Russell slalomed through a series of restaurants that would hand him the keys on off nights so he could cook tasting menus of 10 courses or so. First he inhabited Fitzcarraldo, an Italian restaurant whose combination of industrial, nautical, cinematic and Mediterranean elements has made it a frequent wedding site. Later he moved on to Egg, an austerely contemporary temple to breakfast which had begun its own life, more than a decade earlier, as a pop-up.