For the spice paste, dry-fry the peppercorns, cumin seeds and coriander seeds in a frying pan without any oil for 4-5 minutes, to release the flavours. Transfer the spices to a pestle and mortar and grind.
Place the ground spices into a food processor and add the chilli, shallots, garlic, ginger, lemongrass, lime leaves, cinnamon, turmeric, fish sauce, chilli oil and palm sugar and blend to a smooth paste.
For the duck, score the skin of the duck breasts, season with salt and place into a cold frying pan. Cook over a medium heat, tipping off the fat into a heatproof container as it is released from the duck. (You can keep the duck fat if you wish for roasting potatoes.) Cook the breast for five minutes then turn it over and lightly brown the other side. Remove the duck from the heat and keep warm.
Meanwhile, place a good tablespoonful of paste into the same pan and cook over a low heat until fragrant.
Add the stock and coconut milk and bring to the boil.
Thinly slice the duck breasts and season with salt and freshly ground black pepper. Add the duck slices to the pan and simmer for 2-3 minutes.
Add the spring onions, red pepper and aubergines and cook for five minutes, or until the aubergines are soft and the duck is completely cooked through.
To serve, place a mound of rice onto each of four plates. Spoon equal portions of the duck curry over and garnish with chopped coriander and lime wedges.