This soup celebrates the beautiful ripe heirloom tomatoes of summer. Slow, gentle simmering distills the tomato flavor to its delicious essence, a wonderful payoff for minimal work. Try it when tomatoes are at their peak of flavor (they can even be a little soft for slicing).While the soup is only as good as the tomatoes, if they're a bit too acidic, a teaspoon or two of sugar will make a big difference in taste. Using several varieties of vine-ripened tomatoes makes the soup taste even better. It freezes beautifully, so make enough during the dog days of summer to tide you over the long winter months.
From Food to Live By: The Earthbound Farm Organic Cookbook by Myra Goodman
If you have a food mill, rinse the tomatoes and cut them into large wedges without removing the seeds and skins.
If you don't have a food mill, you'll have to remove the skins and seeds first. Fill a large bowl with ice water and set it close to the stove. Bring a large pot of water to a boil. Using a slotted spoon, lower the tomatoes into the boiling water for about 1 minute to loosen the skins. Remove the tomatoes and plunge them into the ice water, letting them cool enough to handle. Using a paring knife, cut out and discard the cores and slip off the skins. Cut the tomatoes in half crosswise and discard the seeds. Cut large tomatoes into wedges.
Place the tomatoes in a large, heavy-bottom saucepan and add 1/2 cup of water. Cover the pan and cook the tomatoes over medium heat, stirring frequently, until they've completely softened, 15 to 20 minutes. Adjust the heat if necessary so the tomatoes don't scorch, but don't add any mroe water; it will dilute the flavor. Remove the saucepan from the heat and uncover; let the tomatoes cool in the pan, stirring them occasionally to dissipate the heat, about 15 minutes.
If you have a food mill, use it to purée the tomatoes until smooth, discarding the skins and seeds. Or if you've already removed the skins and seeds, purée the tomatoes in batches in a food processor or blender until smooth. If the tomatoes are processed too long, they'll become foamy — but don't worry, the foam will dissipate during cooking and won't affect the taste or appearance of the finished soup.
Transfer the tomato purée to a large, clean pot and reheat it gently, uncovered, over low heat. If the soup is too thin, let it simmer until it's reduced a bit and the flavor has concentrated, 15 to 20 minutes.
Season the soup with salt and pepper to taste. If the soup is too acidic, add 1 to 2 teaspoons of sugar to taste.
If you're not planning to serve the soup immediately, let it cool to room temperature. It can be refrigerated, covered, for up to 5 days, or frozen for up to 6 months. Serve the soup hot, garnished with the shaved parmesan, if desired.