Pat the duck breasts dry and score the skin in a crosshatch pattern, keeping the scores 1/4-1/8 inch apart. Season both sides with salt and pepper.
Place the duck breasts, skin side down, in a large skillet and place over medium-low heat. Cook for 15 minutes.
Flip the duck breasts and cook until they reach an internal temperature of 155°F.
Remove from the heat and set aside to rest for 10 minutes before slicing and serving with the plum sauce, if desired.
To make the plum sauce, combine the chopped plums, water, and a pinch of salt in a saucepan. Cook over medium heat for 5-7 minutes, stirring occasionally. Stir in the soy sauce, rice vinegar, honey, garlic, and ginger. Let it simmer for 10-15 minutes, stirring occasionally, until the sauce thickens and becomes syrupy. Drizzle over the sliced duck.
Notes
Tips: Check out my recipe tips above for perfectly cooked duck breasts.
Leftovers and storage: Store the leftover duck and sauce in an airtight container in the refrigerator for 4-5 days.
Freezer: Let the leftover duck cool completely, then store it in separate shallow containers in the freezer for up to 3 months.
Reheating: I like to reheat the duck in a skillet with a tablespoon of water until warm or microwave for 20-30 seconds.