Submerge the tomatoes in boiling water for 30 seconds, and then place them in a bowl of cold water. Remove the skins.
Cut the jalapeno pepper in half and discard the seeds. Chop the jalapeno finely in a food processor.
Add the onion, pepper, and tomatoes to the food processor and chop coarsely.
Place all the ingredients in a large pot. Simmer for 10 minutes with the top partly covering the pot.
Transfer the mixture to 4 hot, sterilized half-pint jars, leaving 1/2 inch headspace. Process in a water bath for 15 minutes, and then let the jars cool on a wire rack.