Heat the oven to 200C or 400F.
Chop the ends off the courgettes and cut in half lengthways.
Use a teaspoon to scoop out the courgette flesh and seeds onto a chopping board and chop roughly into small pieces (around 1cm / ½ inch).
Pat the courgettes dry with kitchen paper, brush lightly with olive oil (this should use around half of the oil) and sprinkle with a small amount of salt.
Place them into a baking dish and bake in the middle of the oven for 15-20 minutes.
Meanwhile, place a large pan on a medium heat and add the remaining oil.
Add the green chilli and garlic when the oil is hot and fry for a few minutes until fragrant.
Increase the heat and add the courgette flesh and seeds and fry for a few minutes until any water from the courgettes evaporates.
Then add the lamb mince and cook until brown.
Add the harissa paste and season with ground coriander, all spice, cinnamon, cumin and salt.
Continue to cook until the lamb juices have evaporated and remove from the heat.
Then combine the tahini, lemon juice and salt in a small bowl.
Stir in a tiny amount of water (a tsp at a time) until the sauce is just about pourable.
Remove the courgettes from the oven, spoon in the lamb mince and drizzle with the tahini sauce.
Place under the grill / broiler for a further 5 minutes until the tahini sauce starts to brown.
Serve immediately scattered with chopped fresh parsley.