Whisk together vinegar, mustard, salt and pepper. While whisking, add oil in a thin stream until blended. Set aside. Heat a medium-size pot of water to boiling. Add grean beans and cook 4 minutes or until crisp-tender. Drain and rinse with cold water. Tear basil into bite-size pieces. In large salad bowl, toss basil, green beans, tomatoaes, mozzarella and kidney and white beans. Whisk dressing, then drizzle over salad. Toss gendly to coat and serve.