Separate duck breast halves if necessary.
Rinse them under cold water and remove any stray feathers, then pat dry with paper towels.
Score the fat side of each piece three times diagonally. Make sure not to cut through to the flesh.
Sprinkle each side with salt and pepper.
Heat skillet until very hot.
Carefully place each piece of duck breast into the hot skillet skin side down.
Cook on high until golden for approx. 5 mins.
Transfer duck breast pieces to roasting pan skin side up and place in a preheated oven at 425.
Cook for 3-6 mins dependent upon required temperature and thickness of duck breast. If you have a meat thermometer, meat should register at 175 for medium.
Once cooked, transfer to meat board and allow to rest for at least 5 mins.
While duck is resting place vinegar, honey and ponzu into saucepan and place on high heat.
Heat until sauce begins to bubble then lower heat to medium and add Cointreau.
Stir continuously until sauce is reduced by 25%.
Slice duck breast and serve with Cointreau sauce immediately.