Persian-Style Barley and Carrot Soup

In this riff on Persian soup e jo, we toast the barley in a dry pan to bring out rich, nutty flavor. Be sure to use quick-cooking barley, which resembles rolled oats; it softens much quicker than pearled barley. Traditional soup e jo often is thickened with a béchamel sauce. We use sour cream, tempering it with a little of the hot broth and whisking it in off heat to prevent curdling. Sometimes pleasantly tart barberries garnish the soup, though easier-to-find dried currants or cranberries also are delicious. For an even heartier dish, rinse and drain a 15½-ounce can of kidney beans, then add them to the broth after the barley has cooked for 5 minutes.