Heat oven to 275ºF. Arrange the tomatoes in a shallow baking dish or on a cookie sheet. Drizzle half the oil over the tomatoes and sprinkle with the oregano, a few grinds of pepper, and half the salt. Bake about 40 minutes or until the tomato skins pucker and split slightly. Remove from oven. Set oven to broil and toast the bread on both sides until golden (or use a toaster). Remove to a serving dish and immediately rub the cut sides of the garlic into one side of each slice. Sprinkle with the remaining 1/2 teaspoon of salt and drizzle with the remaining oil. Serve the tomatoes on top of the toast. Roasting caramelizes the natural sugars in tomatoes, giving them more sweetness, more intense flavor, and richer color.