Drop beans into saucepan with salted boiling water. Cook until crisp tender, about 3-5 minutes. Drain and let cool.
Cut away the core of each tomato, and cut into wedges.
In a salad bowl, add mustard, vinegar, onions, garlic, EVOO, salt and pepper and blend with a whisk. Add beans and tomatoes, toss well. Sprinkle with basil then serve!