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, & black beans to the mixture. Make dressing by whisking together the White Balsamic, olive oil & salt. Drizzle over bean mixture.
Cover and chill 8 hours, stir occasionally and stir just before serving.