1/2 cup olive oil 2 tablespoons Dijon mustard 6 tablespoons white wine vinegar , divided 4 cloves garlic , minced 2 teaspoons coarse salt freshly cracked black pepper 1 & 1/2 pounds baby red potatoes , quartered 1 & 1/2 pounds baby yellow potatoes , quartered 2 tablespoons chicken broth 4 scallions , diced 1/3…