Four-Bean Salad with Tuna isn't your mama's traditional bean salad. Made with green beans, edamame, kidney and black beans, Four-Bean Salad with Tuna is both healthy and satisfying.
Bring a pot of salted water to a boil. In a serving bowl, whisk vinegar, mustard, honey and oil. Stir in onion; marinate for at least 15 minutes.
Have a large bowl of ice water ready. Blanch green beans in boiling salted water, about 3 minutes. Drain beans and immediately add to bowl with ice water to stop cooking. Drain beans again and pat dry. Cut into thirds crosswise.
Add green beans and remaining ingredients to bowl and toss to combine. Season with salt and pepper.