Fill a large pot with water and bring it to a rolling boil. Add the green beans and blanch for 3 to 4 minutes until bright green. Plunge into ice water to stop cooking.

In the same boiling water, cook the small white potatoes for 15 to 20 minutes, or until fork-tender. Drain and cool for 15 minutes.

While potatoes cool, whisk together balsamic vinegar, Dijon mustard, and minced garlic. Gradually whisk in olive oil until emulsified.

Slice the cooled potatoes in half, add to a large mixing bowl, and combine with blanched green beans. Gently toss together.

Drizzle the dressing over the salad and sprinkle with chopped chives, salt, and black pepper. Toss gently to combine.