Preheat oven to 400 degrees.
Toss the tomatoes lightly with the olive oil on a baking sheet. Spread them out into one layer and sprinkle generously with the coarse sea salt and the pepper. Roast for 15 to 20 minutes, until the tomatoes are soft.
Transfer the tomatoes to a serving platter and sprinkle with basil leaves and sea salt. Serve hot.