Chop the tomatoes and onions and heap them in a large, non-reactive pot. Peel the garlic cloves and slice the jalapeno into quarters, and add it all to the pot, along with a splash of water to prevent burning.

Set the pot over high heat and bring to a boil. Once it bubbles, reduce the heat to medium-high and cook for 25-30 minutes, until the tomatoes and onions are entirely tender.

Fit a food mill with its finest screen and push the tomato mixture through to separate out the flesh from the sauce. Work the pulp until it is very dry.

Return the sauce to the pan and add the vinegar, brown sugar, molasses, and spices.

Bring to a boil and reduce for 45-55 minutes, until the sauce has reduced by approximately half and is quite thick.

While the sauce reduces, prepare your boiling water bath canner and four 12 ounce jars.

When the sauce is ready, funnel it into the prepared jars. Wipe the rims, apply the lids and rings (or lug lids, if you're using sauce bottles), and process in a boiling water bath canner for 20 minutes.

When the time is up, remove the jars from the canner and set them on a folded kitchen towel to cool.

Once they've cooled, check the seals. Sealed jars/bottles can be stored at room temperature until opened. Any unsealed jars should be refrigerated and used promptly.