Green and White Bean Salad with Tuna

In a medium pot of boiling salted water, cook green beans until bright green and crisp-tender, about 3 minutes. Drain, rinse under cool water to stop the cooking, and pat dry.

In a large bowl, whisk together vinegar and oil and season to taste with salt and pepper. Add green beans, cannellini beans, onion, tuna, and pepperoncini and stir to combine. Serve immediately.