The key ingredient in this simple and delicious soup is orzo. Orzo is the Italian word for barley, but names can be deceiving, because orzo is not a grain. And despite its rice shape, orzo is not rice, even though orzo is also known as risoni in Italy. Confused? Don’t be. Orzo is a pasta made from semolina flour, and when cooked it imparts a creamy texture to soups and pasta dishes—and yes, it can also stand in as a substitute for rice, or even as an addition to rice dishes, such as rice pilaf. There are a number of ways to prepare orzo, thanks to its shape. Prepare it as you would pasta, cooking in generously salted water until al dente and serving warm or in a salad. It can also be prepared in a method similar to risotto, where a cooking liquid, such as chicken stock, is gradually …