Nicoise Potato Salad

Ingredients

• 2 pounds small red or white potatoes
• 5 ounces trimmed green beans (cut into 1-inch pieces)
• 1 cup pitted kalamata olives
• 1 cup thinly sliced red onion
• 1/3 cup drained capers ((about 4 ounces))
• 4 hard-boiled eggs (quartered)
• 1/2 cup roughly chopped Italian flat-leaf parsley
• 1/2 cup roughly chopped fresh tarragon
• 1/2 cup extra-virgin olive oil
• 1/3 cup freshly squeezed lemon juice
• 2 tablespoons minced shallot
• 1 tablespoon Dijon mustard
• 1 tablespoon whole grain mustard
• 1 teaspoon kosher salt
• 1 teaspoon freshly ground black pepper