Cook edamame in a large pot of boiling salted water until just tender.
Immerse in ice water to stop the cooking process. Drain and set aside at room temperature in a large salad bowl.
Cook green beans in boiling water for 1 minute or until crisp-tender. Immerse in ice water and drain; add green beans to the edamame.
Add onion, kidney beans, and black beans to the mixture. Make dressing by whisking together the White Balsamic, olive oil and salt. Drizzle over bean mixture.
Cover and chill 8 hours, stir occasionally and stir just before serving.