How to Make It
In a large pot of boiling salted water, cook the beans until just tender, about 4 minutes. Drain the beans and spread them on a large baking sheet to cool. Pat dry.
In a small bowl, whisk the olive oil with the shallots and tarragon and season with salt and pepper. Place the beans and tomatoes in a large bowl, add the dressing and toss well. Transfer to a platter and serve.