How to Make It
In a large saucepan, cover the beets with cold water and bring to a boil. Simmer over moderate heat until tender when pierced, about 45 minutes. Drain in a colander, then rinse in cold water and slip off the skins. Thinly slice the beets crosswise and let cool.
In a large saucepan, steam the green beans until just tender, about 5 minutes. Rinse in cold water and drain well.
In a large serving bowl, whisk the oil with the vinegar and season with salt and pepper. Add the beets, beans, shallots, basil and mint to the bowl and toss to coat, then serve.