Heat your oven to 200°C/Fan 180°C/Gas 6. Quarter the tomatoes and cut the aubergine into chunks. Toss into an ovenproof dish. Sprinkle with 1 tsp cinnamon, some seasoning and 1 tsp oil. Roast for 20 mins till browned and soft.
While the veg roast, peel and finely dice the shallots and garlic. Finely chop half of the coriander leaves. Mix them all in a bowl with the lamb mince and season well. Roll into meatballs around the size of a walnut.
Spoon the roast vegetables into a food processor and blitz to make a smooth sauce. No processor? Use a hand held blender, or mash everything together with a masher. Pour the sauce back into the dish. Taste and adjust the seasoning.
Arrange the meatballs into the sauce - they should be half submerged. Slide the dish back into the oven and roast for 25 mins till the meatballs are browned and cooked through.
Pour the pearl barley into a small pan. Add enough boiling water to the pan to cover the barley by 2 cm. Cover. Bring to the boil, then reduce the heat and simmer for 20-25 mins till tender.
Pick the rest of the coriander leaves off the stems. Drain the pearl barley.
Serve the lamb meatballs and sauce alongside the pearl barley. Finish with a scattering of the remaining coriander.