Chop onion & celery.
Place in large stockpot w/ just enough water to keep them from burning.
Bring to a simmer over med-low heat.
While this simmers, chop the tomatoes.
Add tomatoes to pot & cook until tender.
Run the softened veggies through a food strainer.
Return strained mix to pot.
Add sugar & salt.
Cream butter and Clearjel together, then mix thoroughly with two cups of COLD tomato juice, until dissolved (or blend together in a blender), to avoid lumps in the soup.
Add butter mixture to the rest of the warmed tomato juice.
Heat just until hot. (If it gets to a boil, it can make the soup lumpy).
Just prior to boiling, turn off the burner. It will continue to thicken as it cools.
Ladle into warm, clean jars, leaving 1″ headspace. Wipe the rims of the jars with a clean cloth, then screw on the two piece lids finger-tight.
Process pint jars for 55 min., quart jars 1 hour and 25 min., in a pressure canner at 10 pounds pressure, adjusting for altitude.
Turn off heat and allow the canner to cool completely until the pressure has dropped back to zero before removing the lid. Remove jars and cool on countertop. Check lids to make sure they have sealed properly after 24 hours. If the lid hasn’t sealed, put the jar of soup into the fridge to be eaten within a week.