Step 1Heat the chicken broth and water to a boil in a 5-quart saucepan. Stir in the orzo. Return to a boil. Cook, uncovered, for 10 minutes, stirring occasionally. Drain well and pour into a large bowl. Immediately stir the olive oil and vinegar into the hot pasta.
Step 2Stir in the cherry tomatoes and let stand 15 minutes.
Step 3Add the onions, olives, mint, parsley, oregano, lemon juice, salt and pepper. Toss until all ingredients are evenly mixed. Stir in the chicken.
Step 4Serve immediately. If made ahead and refrigerated, allow the salad to return to room temperature before serving.