Put the chilli and ginger into a mixing bowl. Put the duck into another mixing bowl and season with a generous pinch of salt, tossing to coat evenly. Put the ruby port, soy, vinegar and sesame oil into a third small bowl.
Heat a wok over a high heat and add the sunflower oil. When it starts to smoke add the chilli and ginger and stir fry for a minute. Add the Szechuan peppercorns and fry for 30 seconds.
Throw in the cashews and duck and fry for one to 2 minutes, tossing until the duck is just seared on both sides. Add the chard and brown rice and fry, still tossing, until the chard wilts down.
Toss in the contents of the third bowl and bubble until almost evaporated. Remove from the heat and squeeze over some fresh lime before serving immediately.