In a small sauce pan, blanch the green beans by boiling in liberally salted water for 3 minutes. Drain and cool. In a medium bowl, mix the couscous, beans, tomatoes, shallot, cheese and dressing until combined. Season with salt and pepper. Just before serving, toss in the basil.
If fresh basil is not available, substitute fresh parsley and add 2 teaspoons dried basil. If keeping overnight, toss with an additional tablespoon of dressing before serving.