If using grape tomatoes, cut in half. If using larger tomatoes (if you can get ripe Campari tomatoes, those are excellent here) core and roughly chop the tomatoes.
Combine all ingredients in a large sauté pan. Bring to a boil and then reduce to a gentle boil/hard simmer. Stir occasionally - more as it gets thicker. This can take 1.5 to 2 hours.
Once it has thickened, remove it from the heat but let it rest for a few minutes in the pan where it will thicken a bit more into a jam consistency. Transfer and store in the fridge for up to 2 weeks or freeze.