1) Preheat the oven to 200°C.
2) Toss the tomatoes lightly with olive oil on a baking tray. Spread them out into one layer and sprinkle generously with salt and pepper. Roast for 15 to 20 minutes, until the tomatoes are soft.
3) Transfer the tomatoes to a serving platter and sprinkle with basil leaves and sea salt. Serve hot or at room temperature.