Heat the groundnut oil in a large casserole dish over a moderate heat. Saute the diced lamb in batches until golden brown all over. Remove and drain on a plate lined with kitchen paper.
Add the onion, ginger and garlic to the dish and saute over a reduced heat for 4-5 minutes, stirring occasionally. Add the paste and fry gently for 1-2 minutes, stirring occasionally. Add the lamb and potato back to the dish, then cover with the stock. Bring the mixture to a simmer and cook gently for 25-30 minutes until the potato and lamb are soft.
Once the lamb and potato are soft, adjust the seasoning with the sugar, lime juice, fish sauce and pepper. Remove from the heat and stir in the spinach until wilted. Allow to stand for a few minutes before serving.
Freezing and defrosting guidelines
Cook as instructed and allow to cool completely. Then transfer to an airtight, freezer-safe container, seal and freeze for up to 1-3 months. To serve, defrost thoroughly in the fridge overnight before reheating. To reheat and serve, place on medium heat, stirring occasionally until the dish is heated through.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.