Place 1/4 cup hoisin sauce in a blender or food processor
Add 1/4 cup Shaoxing wine to the food processor
Add 1/2 teaspoon five spice powder to the food processor
Slice 1 thumb of fresh ginger and add to the food processor
Smash, peel and coarsely chop 4 cloves garlic, and add to the food processor
Process until the marinade forms a thin paste.
Pour the marinade into a 12-inch (30 cm) tray or baking dish.
Place the duck into the marinade, fat side up.
Sprinkle salt over the fat.
Preparation
Marinate in room temperature for 30 minutes up to 1 hour, or uncovered in the fridge for a couple hours to overnight.
In this case, bring the duck to your kitchen counter for at least 20 minutes before cooking, so it will return to room temperature.
With a sharp knife, gently score duck breast skin in a tight crosshatch pattern, keeping the scores 1/8 inch apart. If you prefer a little fat left on the breasts after cooking, just barely score the skin; to render more fat, score more deeply, taking care not to expose the flesh.
Season duck breasts lightly with ground black pepper.
Place duck breasts, skin side down, in a large, cold sauté pan and place a smaller sauté pan on top of the duck breasts to press down and keep the edges from curling up.
Place pan over low to medium-low heat. After about 5 minutes, the fat should begin to gently bubble. If the fat is either silent or spitting, adjust heat accordingly. Maintain the gentle bubble of fat, pouring out excess rendered fat throughout the cooking process, until much of the fat has rendered, skin is golden brown, and duck's internal temperature is 125°F (52°C), about 15 minutes.
Increase heat to medium and further brown skin if needed, about 1 minute, before flipping and cooking on the flesh side. For medium-rare meat, cook until breast registers 130°F (54°C) on an instant-read thermometer, about 1 to 2 minutes. Continue cooking until duck registers 140°F (60°C) for medium or 155°F (68°F) for well-done.
Remove duck from pan and set aside to rest for 5 minutes.