We coax caramel-y, nutty notes from dried farro by toasting it on the stovetop until fragrant. Once fully cooked, the still-warm grains then are tossed with dressing, allowing them to absorb flavor as they cool. Crunchy celery and chewy farro provide texture, while feta and olives add pops of bold, briny flavor. Any meaty green olive is good, but plump Castelvetrano olives are particularly nice. Don't use whole-grain farro, which won't cook through in the time indicated. Pearled farro, from which the bran has been removed, is faster-cooking than its whole-grain counterpart. If the front of the package doesn't clearly indicate, check the ingredient list.