Please read Cooking Wildfowl and About Wild Duck and Goose.
Pat dry:
Sprinkle with:
Heat a large skillet over medium-high heat until hot. Add the breasts skin side down and cook until the skin is crisp and browned, about 6 minutes. Turn and cook until the breasts are medium-rare, about 2 minutes more. Transfer the duck to a platter and cover to keep warm. Pour off all but 2 tablespoons of the fat from the skillet. Add and cook, stirring, until softened, 6 to 8 minutes:
Add and cook, stirring, until the mushrooms are softened and have released their juices, about 5 minutes:
Add and stir to coat the vegetables:
Cook, stirring, until fragrant, about 2 minutes more. Add:
Bring to a boil, then reduce the heat to medium-low, and simmer until the liquid has reduced by half, about 10 minutes. Whisk in:
Season the sauce to taste with:
Return the duck breasts to the skillet and heat until warmed through, 2 to 3 minutes.