Slice red onion into thin slices. Place all vegetables in a mixing bowl.
Add cooked and cooled barley. Stir well.
In a measuring cup, whisk together oil, vinegar, lemon juice and spices. Drizzle over vegetables.
Serve garnished with feta cheese and chopped parsley.
Notes
Use the following in place of barley if desired: cooked farro, orzo pasta, bow tie pasta, quinoa, any rice, etc. To make ahead, store dressing separately and add to salad before eating.