Rinse pearl barley under cold water until the water runs clear.

In a medium saucepan, combine barley and 3 cups of water. Bring to a boil, then reduce heat to low, cover, and simmer for 25 minutes or until tender.

Drain any excess liquid from the barley and spread it on a baking sheet to cool to room temperature.

In a large mixing bowl, whisk together olive oil, lemon juice, salt, and pepper to create the dressing.

Add the cooled barley, chickpeas, cucumber, tomatoes, onion, and parsley to the bowl.

Toss all ingredients until evenly coated with the dressing.

Fold in feta cheese if using.

Serve immediately or refrigerate for 30 minutes to allow flavors to meld.