- 2½ pounds fresh, sweet, mature vine-ripened plum tomatoes
- 1 small carrot, scraped and grated or chopped
- ¼ small red or yellow onion, finely sliced or chopped
- 5 fresh basil leaves, torn, plus additional basil leaves for serving
- ½ teaspoon salt
- 3 tablespoons unsalted butter or extravirgin olive oil
- Cut out the tough area around the core of each tomato. Cut the tomatoes into halves crosswise and squeeze out the seeds, then chop coarsely. Place them in a heavy saucepan with the carrot, onion, the 5 basil leaves, and salt. Bring to a boil, then reduce the heat to medium. Simmer, uncovered, for 20 minutes, stirring frequently to prevent the tomatoes from sticking to the bottom of the pan. At this point, a fairly thick mixture should have formed. If it is excessively watery, simmer for an additional 5 to 10 minutes. Remove from the heat.
- When the mixture has cooled somewhat, pass it through a food mill positioned over a clean saucepan, being sure to press the remaining pastelike mixture thoroughly in order to extract as much fiber as possible. You should have a light sauce, thick enough to coat a spoon. If the sauce is too thin, simmer it, uncovered, for another 10 minutes or so to evaporate it further. Just before serving, tear the remaining basil leaves into small pieces and stir them in along with the butter or olive oil. Check for seasoning.