Preheat the oven to 190°C.
Cut the meat into 1 cm thick slices.
Cut the orange in half, squeeze the juice into a small bowl, then cut the flesh into 4 wedges.
Mix the orange juice with the marmalade, chilli and vinegar. Season with salt and pepper.
Put the duck slices into the marinade, glaze them well.
Line a baking tray with baking paper, then put in the duck slices side by side. Brush them with any remaining marinade and place the orange pieces around them.
Roast for about 10-15 minutes, depending on how well-cooked you prefer your duck.