In a small bowl, whisk the vinegar with the olive oil and season with salt and pepper. Add the tarragon.
In a large pot of boiling salted water, cook the asparagus until just tender, about 3 minutes. Using tongs, transfer the asparagus to a colander and refresh under cold water. Drain and pat dry. Cut the asparagus into 3-inch lengths.
Add the beans to the boiling water and cook until tender, about 5 minutes. Drain the beans in the colander and refresh under cold water. Drain and pat dry.
In a bowl, toss the cooked vegetables, tomatoes and dressing and serve.
The dressing, asparagus and beans can be prepared through Step 3 and refrigerated overnight.