Tomatoes intensify and sweeten after long, slow cooking. I use the same technique for all tomatoes, whether sweet cherry tomatoes or the meatier Romas.
Whole Tomato Version (perfect for cherry tomatoes)
Preheat oven to 325°F.
Toss everything together in a bowl, then put it into a rimmed baking pan or other ovenproof pan.
Bake for 2 hours or until tomatoes look wrinkled, blistered, and slightly reduced.
Sliced Tomato Version (perfect for plum tomatoes and slicers)
Preheat oven to 300°F.
Slice the tomatoes half-inch thick and lay on a silpat-covered sheet pan. Drizzle with olive oil, then season with herbes de Provence, onion powder, garlic powder, sea salt, black pepper, and herbs.
Bake for 2 hours or until the tomatoes have shrunk and lost a lot of moisture.
Notes
The tomatoes will keep for about a week in an airtight container in the refrigerator.