1. To make the chermoula,put everything in a blender and purée.
2. Place a tagine or heavy-bottomed casserole dish over a low-medium heat. Add the olive oil,then the onion,potato and chermoula,and cook for about 5 minutes,until soft.
3. Add the peas,tomatoes,honey,salt,lemon juice and 1 cup of water and bring to the boil. Reduce the heat to a simmer and cook for about 30 minutes.
4.Add the prawns and cook gently for about 3-4 minutes,turning once. Spoon onto 4 plates and sprinkle with the coriander leaves and chilli rounds. Serve with steamed couscous.