- Mix tomatoes, onion, Serrano peppers, green peppers, and cabbage with half of salt. Put in a colander set inside a bowl to drain overnight.
- Sanitize jars and have them ready in water bath.
- Combine all ingredients in a stainless steel pot and bring to a low simmer, skimming any foam that rises to the top. Continue cooking and skimming until reduced by a third.
- Add mixture into prepared canning jars and process for 10 minutes.
- Let jars rest for a few days before eating to allow flavors to develop.