1.Make the paste first: In a dry frying pan add the peppercorns, cloves coriander & cumin seeds. Cook over a medium heat until they become aromatic. Cool slightly and place in a mortar and pestle.
2. Grind the spices, adding the nutmeg until finely ground.
3. Add the lemongrass and grind until very fine, then add the garlic and galangal and pound until paste-like.
4. Remove mix from the mortar and place in a bowl. Grind the chillies using the mortar and pestle, add the salt and then the shallots. Grind until a fine paste is achieved then add the lemon zest (reserving the juice) and the shrimp paste.
5. Mix in the spice and lemongrass mix and combine.
6. Curry: In a frypan, fry the duck legs skin side down for around 4 mins, until golden, then 1 min on meat side, set aside.
7. In a heavy based saucepan, add 4 tablespoons of coconut milk and heat.
8. Add the curry paste and the green chilli and cook for 2 mins, then add the duck legs.
9. Add the coconut milk and the tomatoes, then the whole kaffir lime leaves.
10. Simmer on low for 1.5 hours, stirring occasionally. Then add the sweet potato and cook for a further 20 mins or until the sweet potato is cooked and the duck is tender and falling off bone.
11. Adjust the seasoning with fish sauce, palm sugar and reserved lemon juice as required.
12. Add the snow peas and stir in then transfer to a serving bowl and garnish coriander leaves. Serve with Cardamom and Saffron Pilaf.