You can use kalamata olives or other black olives in place of Nicoise olives if they are hard to find.
1 pound green beans, trimmed
1 cup halved cherry tomatoes
2 tablespoons extra-virgin olive oil
1-1/2 tablespoons red wine vinegar
1 tablespoon minced shallots
1/2 cup pitted, chopped Niçoise olives
A pinch of dried thyme
Kosher salt and freshly ground black pepper
Bring a medium pot of well-salted water to a boil over high heat and cook the green beans until crisp-tender, about 3 minutes; drain and cool under cold running water. In a large bowl, combine the beans with the cherry tomatoes.
In a small bowl, whisk the olive oil, vinegar, and shallots. Stir in the olives, thyme, and salt and pepper to taste. Toss the vegetables with the vinaigrette, adjust the seasoning, and serve.