This colorful salad is a great way to showcase fresh green beans and ripe tomatoes. The salad starts with blanched green beans that are tossed with sliced cherry tomatoes, red onion, and crumbled feta cheese. The salad is dressed with a simple vinaigrette made with olive oil, red wine vinegar, and Dijon mustard. The result is a refreshing and flavorful salad that is perfect for summer picnics and barbecues.