Bring a large pot of salted water to a rolling boil. Add orzo and cook until al dente according to package directions, usually 8–9 minutes. Drain and rinse under cold water until cool, then shake off excess water and transfer to a large mixing bowl.

In a small bowl or jar, combine olive oil, lemon juice, lemon zest, minced garlic, oregano, Dijon mustard, salt, and pepper. Whisk vigorously or shake until well emulsified.

To the bowl of cooled orzo, add halved cherry tomatoes, diced cucumber, red onion, olives, and fresh herbs. Pour the dressing over everything and toss gently to coat. Fold in the crumbled feta last to keep chunks intact.

Cover the bowl and refrigerate for at least 30 minutes (or up to 24 hours) to let the flavors meld. Just before serving, give it another quick toss and garnish with extra herbs and lemon wedges.