Preheat oven to 190Line a baking tray with baking paper.
Transfer duck legs to the tray – remove the gelatinous stock and place in a small saucepan. Place baking tray on the middle rack in the oven to heat through, for about 10 minutes.
Place the small saucepan with the gelatinous stock over medium-high heat. Add plum sauce and stir. Bring to the boil and turn off.
Meanwhile, heat 1 tablespoon oil in a large frying pan or wok set over medium-high heat. Add beans and stir fry for 2-3 minutes, they should be lightly charred but still firm. Transfer to a large bowl.
Return frying pan or wok to the heat. Add another tablespoon oil and stir-fry zucchini noodles for 2 minutes. Transfer to the same bowl.
Return frying pan or wok to the heat. Add the remaining oil and cook the stir-fry mix for 4 minutes. Transfer to the bowl.
Turn the oven setting to grill and grill the duck legs for a further 2 minutes. Remove from oven.
Divide the stir-fry between 4 bowls and, using tongs, place a duck leg on top of the stir-fry. Drizzle with the plum sauce and sprinkle with sesame seeds. If using, garnish with sliced spring onions and coriander leaves.
Note: Leftovers, if there are any, can be served with the meat shredded as a cold salad the next day or in a wrap!