Canned Tomato Soup

Place tomatoes, celery, and onions into a large pot. Pour in just enough water to cover vegetables; bring to a boil. Reduce heat and simmer until tomatoes are tender, 20 to 30 minutes. Pour through a strainer or food mill, discard solids, and return liquid to the pot; stir in sugar and salt.

Blend together butter and flour in a blender until smooth and creamy; pour in tomato juice. Blend until smooth, then pour into liquid in the pot. Cook and stir over medium heat just until tomato soup is hot.

Sterilize the jars and lids in boiling water for at least 5 minutes. Pack tomato soup into the hot, sterilized jars, filling to within 1/4 inch of the top. Run a knife or thin spatula around the insides of the jars to remove any air bubbles. Wipe the rims with a moist paper towel to remove any residue. Top with the lids and screw the rings on tightly.

Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower the jars 2 inches apart into boiling water using a holder. Pour in more boiling water to cover the jars by at least 1 inch. Bring water to a rolling boil, cover the pot, and process for 20 to 30 minutes.

Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, until cool. Press the center of each lid with a finger to ensure the lid does not move up or down. Store in a cool, dark area. Wait at least 12 hours before opening.