Plum tomatoes, sometimes called roma tomatoes, are a meaty, oval-shaped tomato. They have small seeds, little juice, and a mild, rich flavor, making them especially good for this pasta sauce.
In a large kettle bring 4 inches of water to boiling. Immerse tomatoes, a few at a time, in boiling water for 1 minute. Drain in a colander; peel, seed, and chop tomatoes. (You should have 10 cups.)
In the same kettle cook onion, celery, and garlic in hot oil about 5 minutes or until tender. Add chopped tomatoes, sugar, salt, pepper, and cayenne pepper, if desired. Bring to boiling; reduce heat. Simmer, uncovered, for 45 minutes, stirring occasionally. Stir in oregano and thyme. Simmer, uncovered, for 15 minutes more. Cool slightly.
In a food processor bowl process sauce, one fourth at a time, to desired texture. (Or, put sauce through a food mill.) Place sauce in a bowl set in ice water to cool quickly. Fill 3 or 4 freezer containers; seal tightly, label, and freeze up to 6 months.
To thaw one portion, remove from freezer container and place in a saucepan. Cook over medium heat until hot, stirring occasionally. (Or, in a 1-quart microwave-safe casserole cook on 100 percent power (high) for 12 to 14 minutes, stirring occasionally.) Serve hot sauce over pasta. Makes 3 or 4 pints (about nine 3/4-cup servings).