Fill a hot water canner about 2/3 rds full with water and bring it to a boil. 

Wash jars and screw bands in hot soapy water; rinse with warm water. Pour boiling water over flat lids in a saucepan off the heat. Let stand in hot water until ready to use. Drain well before filling.

Make sure you are starting with peeled tomatoes. If you don’t know how to peel tomatoes for canning, pop on over to my How to Peel Tomatoes tutorial real quick. It will make the process go more smoothly.

Combine the tomatoes, onions and peppers in a large heavy pot. Bring ingredients to a boil over medium high heat. Reduce heat and simmer for about 5 minutes, stirring occasionally to prevent scorching and to let the vegetables soften a bit. 

Puree the mixture using a food processor or food mill.

Cook the puree over medium high heat until thickened and reduced by half {this took 1 hour 15 minutes for me}. 

Place cinnamon, all spice, mustard seed and celery seed in a spice bag and cinch tight. Add spice bag along with sugar, paprika and salt to the mixture and simmer for 30 minutes, stirring often to prevent scorching. 

Add vinegar and simmer until the sauce has thickened {about 20-30 minutes} making sure to stir often to prevent scorching. 

Remove the spice bag. 

Ladle ketchup immediately into prepared jars, filling to within 1/4 inch of tops. Remove any air bubbles. 

Canning Tomato Ketchup

Wipe the jar rims and threads clean if needed. If using traditional canning jars, cover with 2-piece lids. Screw bands on.

If using Weck jars, carefully place the Weck rubber gasket on the lid of the jars. Place the lid on the jar and secure the lid with 2 evenly spaced Weck clamps. 

Place jars on an elevated rack in a hot water bath canner. Lower rack into canner. {Water must cover jars by  2 inches. Add boiling water, if necessary.}

Cover; bring water to a boil. Process 10 min. Remove jars and place upright on a towel to cool completely. Cool jars for 12-24 hours. 

After the jars have cooled, check the seals by pressing the middle of the lids with your finger. If lids spring back, lids are not sealed and refrigeration is necessary. {Traditional canning jars}. 

For Weck jars, check to make sure your seal is pointing downwards. 

Remove rings or clamps and store jars in a cool dark place. 

Yields about {6} half pints or about {36} #080 Weck Mini Mold jars