Preparation

• Prepare a medium-high (400°F to 475°F) gas or charcoal grill fire.
• Place each chicken breast between two sheets of parchment paper and pound with a kitchen mallet to a uniform thickness. Brush both sides of the chicken with the vegetable oil, and season generously with salt and pepper. grill, turning once, until cooked through (165°F), 6 to 10 minutes. Transfer to a cutting board, tent with foil, and let rest 5 minutes.
• Meanwhile, in a small bowl, combine the vinegar, shallot, mustard, and sugar. Whisk in the olive oil; stir in the olives and parsley.
• Thickly slice the chicken and serve with the vinaigrette spooned over it.