Generously salt and pepper both sides of the chicken breasts.
In a small bowl, whisk together the Extra Virgin Olive Oil, O Citrus Champagne Vinegar, mustard, and rosemary marinade.
Place chicken in an airtight marinating container (such as a glass storage container) or in a Ziploc bag. Pour the marinade over the chicken, seal container/bag, and shake to make sure chicken is evenly coated with the marinade. Place in refrigerator for 30 minutes, or up to 24 hours.
When ready to fire up the grill, take the marinated chicken out of the refrigerator and let it sit at room temperature while you preheat the grill to medium. Grill the chicken breasts for about 4 to 5 minutes on each side, or until the juices run clear. Be careful not to overcook the chicken.
Remove the cooked chicken from the grill and let rest for 5 to 10 minutes. Slice the grilled chicken breasts into 1 inch serving portions and place in serving dish. Garnish with rosemary sprigs and thin lemon slices. Enjoy!
