1. In a large serving bowl, combine the chick peas, onion, celery, garlic, and dillweed, and the parsley if used. Add the vinegar, oil, salt, and pepper, and toss to blend.
2. Break the tuna into chunks and add it to the salad along with the tomatoes if used. Toss gently to blend. Serve on the lettuce leaves at room temperature or slightly chilled.