Heat oven to 400°F. In a medium bowl, toss together tomatoes, oil, and salt. Spread tomatoes in a single layer on a baking pan and roast for 15 to 20 minutes, or until soft and wrinkly. Halfway through roasting, shake pan to turn tomatoes. Let cool 5 minutes before serving. Store in an airtight container for up to 2 weeks in the refrigerator.