Chop tomatoes, peppers, and onions.
Wash all canning jars, screw tops, and lids. Allow to drain dry or dry in the dishwasher.
Add to a large pot and bring to a boil slowly – about 1 ½ hours..
Add salt, sugar, cinnamon, and vinegar.
Boil longer to dissolve the sugar.
Ladle into canning jars, leaving a ½ inch head space..
Working fairly quicklly as you don't want the sauce to cool in the jars. Cooling runs the risk of the jars breaking when added to the canner of boiling water for processing. Remove air bubbles from each jar by using the blade end of a dinner knife or a chop stick.
Wipe the rim of each jar.
Screw on each lid “fingertip tight.” Be careful not to screw on tightly to allow for expansion, but tight enough to apply pressure to the lid to seal while boiling and cooling.
Carefully set in canning rack and gently lower into canner of boiling water. Wait for water to come to a boil again and begin timing 20 minutes.
Remove jars and allow to cool. After 24 hours, check to make sure jars are sealed. The center of the lid should not move up and down when the center is pressed. No doubt you'll hear a "pop" sound as each jar seals.