Core the tomatoes and chop them roughly. Put them, with all the other ingredients, in a large nonreactive pot. Bring to a boil over high heat, then reduce heat to low.
Simmer the jam, stirring regularly, until the tomato appears fully cooked and begins to break down.
Meanwhile, prepare one more jar than you’ll think you need. The jars do not have to be sterile, but they do need to be sparkling clean. I like to take clean jars right out of the dishwasher. Wash the lids in warm sudsy water, then rinse and set aside with the bands. Put a saucer or small plate in your freezer to chill (this will be for testing doneness.) Have an extra small jar, or custard cup, clean and ready for any excess.
Back to the cooking pot of tomatoes! By now, they will be fully cooked, and beginning to break down. Blitz with an immersion blender, getting it as smooth as possible.
Continue cooking the smooth tomato jam until it’s thick and gloppy. I test for doneness by putting a spoonful on a saucer, and chilling it in the refrigerator for 2 minutes. After that time, if I can drag my finger through the jam, and leave a clear track that doesn’t fill in again, it’s ready.
When the jam is ready, remove the pot from the heat. Ladle jam into prepared jars. Wipe the jar rims, apply lids and bands, then process for 20 minutes in a steam canner or boiling water bath.This spiced tomato jam is denser than most jams and jellies, and therefore requires a longer processing time. The time is the same for both 4-oz and 8-oz jars.