01 - Set the oven temperature to 350°F.
02 - Pat the duck legs dry with paper towels and season thoroughly with salt, black pepper, and five-spice powder if using.
03 - Place the duck legs skin side down in a cold, ovenproof skillet over medium heat and cook for 8 to 10 minutes until the skin is golden and fat has rendered.
04 - Flip the duck legs, transfer the skillet to the oven, and roast for 1 hour, basting halfway through with rendered fat until skin is crisp and meat tender.
05 - In a medium saucepan, combine plums, honey, brown sugar, red wine vinegar, soy sauce, shallot, garlic, fresh ginger, red pepper flakes, and water. Bring to a simmer over medium heat.
06 - Simmer the mixture, stirring occasionally for 20 to 25 minutes until the plums are soft and the sauce thickens. Mash or blend to desired consistency and adjust seasoning.
07 - Remove duck legs from the oven and allow them to rest for 5 minutes.
08 - Plate the duck legs, spoon the plum sauce over, and garnish with sliced spring onions and chopped herbs as desired.