1. Score the duck skin with a thin sharp knife. Season the breasts with salt and pepper.

2. Heat the oil in a large frying pan over medium heat. Add the mushrooms and scallions and cook, stirring often, about 5 minutes, until the mushrooms are tender. Stir in the lemon juice and tomato paste.

3. Dissolve the cornstarch in ¼ cup of the stock and return to the remaining stock. Stir into the mushroom mixture. Bring to a boil, stirring often, until simmering and thickened. Stir in the parsley and season with salt and pepper. Remove the sauce from heat and keep warm.

4. Heat a ridged grill pan over medium-high heat. Add the duck, skin side down. Cook until the skin is golden brown, pouring off the fat as needed, about 8 minutes. Turn and cook about 2 minutes more, until the duck is medium-rare.

5. Place the duck on a platter and tent with aluminum foil. Pour off any fat in the pan. Return to medium-high heat. Add the wine and stir to release any browned bits in the pan. Stir into the sauce.

6. Slice the duck and transfer to dinner plates. Top with the sauce, and serve hot.