If you like, trim the stems of the mushrooms even with the caps—they will look neater that way. Save the stems for vegetable stock or chop them for a vegetable soup. The mushrooms keep for a few days in the refrigerator. If you want to keep them longer, top them off with enough oil and vinegar to cover them completely. The oil will float to the top and seal out air. They’ll keep a couple of weeks like this.
Cooks' Note
Choose firm, unblemished mushrooms without exposed gills for this preparation. They will look nicer after pickling.
