Heat a non-stick casserole pan with a lid until hot, then add the lamb and brown all over. Then add the onion and cook for 3-4 minutes until soft. Tip in the harissa and tinned tomatoes, then fill the empty tomato tin up with water and add that to the pot. Add a chicken stock cube or equivalent in concentrated liquid stock.
Simmer for 45 minutes, then add the squash and chickpeas and keep cooking, uncovered, until the squash is tender. This should take another 20-25 minutes. Stir in the parsley and serve.