Potato Salad with Green Beans and Tarragon

Ingredients

• 1 lb white or red-skinned boiling potatoes, diced 3/4"
• 1/2 lb trimmed fresh green beans
• 2 Tbs chopped fresh tarragon (2 tsp dried)
• 1 Tbs Dijon mustard
• 2 Tbs extra-virgin olive oil
• 1 Tbs white-wine vinegar
• 1 tsp salt
• 1/4 cup chopped scallions
• 1/4 tsp freshly ground black pepper