Bring a large pot of salted water to a boil. Add beans and bring back to a boil. Cook until beans are bright green and just tender but not softened, about 3 minutes. Drain and rinse beans immediately under cold running water. Transfer to a paper towel-lined plate and gently pat dry.
Just before serving, combine herbs, vinegar and oil in a large bowl. Whisk well to blend ingredients. Add beans and tomatoes, season with salt and pepper and toss gently to combine. Serve at room temperature.