Bring broth and quinoa to a boil in a saucepan. Reduce heat to medium-low, cover, and simmer until quinoa is tender and water has been absorbed, 15 to 20 minutes. Transfer quinoa to a large bowl and set aside to cool, about 10 minutes.
Mix tomatoes, parsley, kalamata olives, onion, feta cheese, olive oil, vinegar, and garlic into quinoa. Squeeze lemon juice over quinoa salad, season with salt and pepper, and toss to coat. Chill in refrigerator, 1 to 4 hours.