Heat your oven to 180°C/Fan 160°C/Gas 4. Warm a deep frying pan or wok for 1 min. Add ½ tbsp olive oil and the lamb mince into the pan. Cook and stir for 8 mins till the lamb has browned all over.
While the lamb cooks, peel and finely chop the onion. Halve the pepper and scoop out the seeds and white bits. Finely chop it. Trim the top off the aubergine and dice it. Peel and grate or crush the garlic.
When the lamb is brown, scoop it out onto a plate. Add the onion, pepper and aubergine to the pan. Season well with salt and pepper. Cook and stir for 10 mins to soften and brown the veg.
Add the lamb back to the pan. Stir in the garlic. Measure out 1 tsp Cajun seasoning and stir into the pan. Add most of the thyme sprigs. Pour in 100ml warm water. Take off the heat.
Tip the polenta, 1 tsp baking powder and a good pinch of salt and pepper into a bowl. Whisk together. Pour in 100g of the yogurt and 8 tbsp warm water. Stir together with a fork to make a stiff, dry dough.
Divide the lamb mix between two small ovenproof dishes (or one medium one), discarding the thyme sprigs. Crumble over the cornbread dough. Bake for 20 mins till the cornbread is golden brown.
Serve the Cajun lamb bakes with the leftover yogurt, garnished with the remaining thyme leaves.