Heat a large saucepan and gently fry the onion in a little olive oil for 10 minutes. Add the diced lamb, the garlic, red pepper and tomato puree. Stir in the tomato base sauce, or tinned tomatoes, water and basil. Add salt to taste, cover with a lid or a couple of tight layers of foil, then simmer on a low heat for around 1½ hours or transfer into a deep baking tin cover with foil and finish cooking it in the oven at 150°C/300°F/gas 2 for about 2 hours, or until the meat is tender.
Tip the dry couscous into a serving tin. Then pour the boiling vegetable stock on to the couscous - it should just cover it. Leave to stand for 10 minutes and then fluff up with a fork just before serving.
Serve the lamb with couscous and a mixed leaf salad.