Heat the oven to 200oC (400oF). The recipe can also be cooked in a small toaster oven.
Put the tomatoes in a medium sized bowl. Add the oil, cumin, sugar, garlic, thyme sprigs, oregano sprigs, lemon strips, a pinch of salt and a good grind of pepper. Toss together with your hands.
Put the tomatoes on a foil sheet with sides turned up that’s just large enough to accommodate them all snugly. Place in a baking tray, roast for 10 minutes until the tomatoes are beginning to blister and the liquid is bubbling, then turn the oven to the grill setting and grill for 5 to 7 minutes, until the tomatoes start to blacken on top.
While the tomatoes are roasting, mix the yoghurt with the grated lemon zest and 1/4 tsp salt, then return to the fridge.
Once the tomatoes are ready, spread out the cold yoghurt on a large plate or shallow, wide bowl. Spoon the hot tomatoes on top, as well as the pan juices, lemon peel, garlic and herbs, and garnish with some of the remaining oregano and thyme as well as some chilli flakes. Drizzle with olive oil and serve at once with some warm flatbreads or crusty baguette slices.