In a stock pot, combine the tomatoes, onions, peppers, sugar and salt; simmer, uncovered, for 45 minutes.
Place the pickling spices, celery seed and mustard seed on a double thickness of cheesecloth; bring up corners of cloth and tie with string to form a bag; add to tomato mixture. Cook for 45 minutes or until very thick, stirring frequently.
Add vinegar; cook to desired thickness. Discard spice bag. Carefully ladle hot mixture into hot pint jars, leaving 1/2-in. headspace. Adjust caps. Process for 15 minutes in a boiling-water canner.
Editor’s Note: When cutting hot peppers, disposable gloves are recommended. Avoid touching your face. The processing time listed is for altitudes of 1,000 feet or less. For altitudes up to 3,000 feet, add 5 minutes; 6,000 feet, add 10 minutes; 8,000 feet, add 15 minutes; 10,000 feet, add 20 minutes.
Wear disposable gloves when cutting hot peppers; the oils can burn skin. Avoid touching your face.