Make couscous according to package instructions. Pro tip: As cooking liquid use preferably a flavourful chicken or vegetable broth.
Heat oil in a large saucepan over medium-high heat, add onion, carrot, capsicum, chilli and garlic and sauté until tender (6-7 minutes).
Stir in spices until fragrant, then add tomatoes, chickpeas and stock, season to taste and simmer until well flavoured and slightly thickened (5-10 minutes).
Add prawns and preserved lemon, simmer until prawns are just cooked through, add lemon juice and check seasoning.
Serve hot spooned over couscous, scattered with mint and coriander, with yoghurt to dollop.