1/2 cup olive oil
1/2 cup sliced fresh mint
1 tablespoon honey
1 tablespoon Dijon mustard
2 lemons, zested and juiced
1/2 medium shallot, finely chopped
Kosher salt and freshly ground black pepper
4 boneless skinless chicken breasts (6 to 8 ounces each)
1 3/4 cups low-sodium chicken broth
1 cup quick-cooking barley
1 1/2 cups mixed red and green seedless grapes, halved
1/4 cup chopped walnuts
2 radishes, halved and thinly sliced
1 stalk celery, thinly sliced