Season with salt and pepper the duck and put it in a pan skin-side down and fry until crispy. Turn it over, fry it for 30 seconds over high heat then turn the heat down and gently cook for 5-7 minutes to your liking. Alternatively grill it in the oven skin side up.
Let the duck rest for 5 minutes while you prepare the dressing.
Whisk the fish sauce, ginger, lime & orange juice, add the grated ginger and chilli pieces (you can use some of the cooking juices too).
Slice the duck diagonally and serve with the dressing drizzled over it.