Heat 1 tablespoons oil in a large non-stick frying pan over medium heat and brown the lamb with the ground cumin and coriander. Transfer to the slow cooker.
Using the same frying pan, add the remaining oil and fry the onion, garlic and harissa paste for a few minutes until softened before transferring to the slow cooker with the lamb.
Add the chopped tomatoes, tomato purée and 250ml of stock to the slow cooker. Cover and cook on HIGH for 2 hours.
Add the chickpeas, coriander stalks, butternut squash, lemon, apricots and the remaining stock.
Stir well, cover and cook on HIGH for a further 1.5 hours, or until the lamb is tender and the sauce is a good consistency.
About 20 minutes before serving, season, if required and add the freshly chopped coriander leaves.
Serve with wholewheat couscous, or your favourite grains, or pasta.