This easy three-bean salad can be served warm or at room temperature. It makes a nice side dish for grilled pork, blackened fish or chicken.
In a large pot of boiling salted water, cook green beans until bright green and crisp-tender, 2 to 3 minutes. Drain and rinse under cold water until cool. In a large bowl, whisk together vinegar, oil, oregano, shallot, and mustard. Add green beans, red kidney beans, and chickpeas; toss well to combine. Season with salt and pepper.