Wash tomatoes; remove stem ends and cores.
In slow-cooking pot, combine tomatoes, celery, and onions.
Cover and cook on low for 8 to 10 hours.
Press through food mill or sieve.
Return juice to pot.
Cook on high for 30 minutes.
Add lemon juice, sugar, salt, horseradish, Worcestershire sauce, and hot sauce.
Cook on high for another 10 minutes.
Makes about 6 cups.