Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Combine tomatoes, onions, green and red peppers, vinegar, brown sugar, garlic, horseradish, if using, celery salt, mustard seeds and salt in a large stainless steel saucepan. Bring to a boil over high heat, stirring frequently. Reduce heat and boil gently, stirring occasionally, for 1-1/2 hours, until sauce begins to thicken. Add allspice, mace, cinnamon and cloves. Continue to boil gently, stirring occasionally, until thickened and sauce begins to mound on a spoon, about 30 minutes.

Ladle hot sauce into a hot jar leaving a ½ inch headspace. Remove air bubbles. Wipe jar rim. Center lid on jar and apply band, adjust to fingertip tight. Place jar in boiling-water canner. Repeat until all jars are filled.

Water must cover jars by 1 inch. Adjust heat to medium-high, cover canner, and bring water to a rolling boil. Process pint jars for 20 minutes, adjusting for altitude. Turn off heat and remove cover. Let jars cool 5 minutes. Remove jars from canner; do not retighten bands if loose. Cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.