Ingredients

• 12 ounces new potatoes, quartered
• 2 bunches scallions, trimmed
• 4 tablespoons extra-virgin olive oil, divided
• ¾ teaspoon ground pepper, divided
• ½ teaspoon salt, divided
• 4 large boneless, skinless chicken thighs (1-1 1/4 pounds), trimmed
• 2 tablespoons sherry vinegar
• 2 tablespoons chopped fresh herbs, such as dill, thyme and/or parsley
• 1 tablespoon whole-grain mustard
• 1 tablespoon finely chopped shallot