Preheat the oven to 350 degrees F. Place the tomatoes, cut-side-up, in a sided baking pan. Drizzle the tomatoes with the 1/4 cup oil; and then top with garlic and chili flakes, salt and pepper. Roast the tomatoes 30 minutes, and then remove from the oven and sprinkle with the oregano. Cool tomatoes to room temperature, and then transfer to a tightly sealing jar, ensuring all the juices in the pan make it into the jar. Pour the 2 Tbsp. olive oil over the tomatoes, and then seal the jar. Refrigerate and let the tomatoes marinate and build flavours in the jar overnight.
To serve, let tomatoes warm at room temperature 20 minutes, and then enjoy.