This can be made up to 3 days in advance, up to the point of the yogurt being added. Keep in the fridge until needed. Feeds 4 as a starter or side, and 2 as a main.
Preheat oven to 475 degrees F.
Place eggplants on a baking sheet and roast for 1 hour,turning them over halfway through, until the flesh is completely soft and slightly smoky. Remove from the oven and, once cool enough to handle, scoop the flesh out into a colander. Set aside in the sink or over a bowl, for 30 minutes, for any liquid to drain away. The skin can be discarded.
Place the cherry tomatoes on the same baking sheet and roast for 12 minutes, until slightly blackened, split, and soft. Remove from the oven and set aside.
Meanwhile, if starting with uncooked lentils, fill a medium saucepan with plenty of water and place over high heat. Once boiling, add the lentils, decrease the heat to medium, and cook for 20 minutes, until soft but still retaining a bite. Drain, then set aside to dry out slightly. If starting with ready-cooked lentils, just tip them into a large bowl and add the eggplant flesh, tomatoes, oil, lemon juice, garlic, 2 tbsp of oregano, 3.4 tsp salt, and a good grind of pepper. Mix well, then spoon into a large shallow bowl. Top with the yogurt, swirling it through slightly so there are obvious streaks. Sprinkle the remaining 1 tbsp of oregano over the top, drizzle with a little oil, and serve.