The secret is in a) the quality of the ingredients, and b) the slow roasting. Roasting tomatoes does wonders for their flavor, simultaneously intensifying and softening it until, well, magic.
The following recipe is adapted from Simple to Spectacular, by Jean-Georges Vongerichten and Mark Bittman. Serves 4 to 6.
12 plum tomatoes, ripe but not mushy*
1/3 cup extra-virgin olive oil
6 garlic cloves, minced*
1 tbsp dried thyme*
1 1/3 tsp coarse salt*
1. Preheat oven to 275 degrees F.
2. Cut out tomato core and cut an X into the smooth end. Drop tomatoes in boiling water for about 15-20 seconds, or until the skin loosens, then transfer to a bowl of ice water. Peel tomatoes, cut in half lengthwise, then scoop out seeds and pulp.
3. Line a baking sheet with aluminum foil, and place tomatoes cut side down onto sheet. Cover tomatoes with olive oil, then sprinkle evenly with the garlic, thyme and salt.
4. Place in oven and cook for two hours or more, turning both the tomatoes and the baking sheet every 30 minutes. Serve with French bread.
*original recipe calls for 12 plum tomatoes OR 6 large tomatoes, 6 cloves of garlic, peeled and lightly crushed, 6 sprigs thyme, and 1 tsp coarse salt.