Picnic Potato Salad with No Mayonnaise

2 pounds small new potatoes, quartered

2 tablespoons balsamic vinegar

¼ cup extra-virgin olive oil

1 tablespoon Dijon mustard

2 tablespoons chopped fresh basil

½ teaspoon salt

¼ teaspoon ground black pepper

½ cup chopped onion

¾ cup crumbled blue cheese

2 tablespoons chopped fresh chives

Place potatoes into a large pot and cover with lightly salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, 10 to 15 minutes; drain.

Whisk vinegar, olive oil, mustard, basil, salt, and pepper together in a large bowl; add the potatoes and onion. Toss gently to coat. Let stand until cool, about 30 minutes.

Fold blue cheese and chives into potato salad until blended.