Heat the oil in a pan on medium heat and roast the tomato paste and onions well. Add the sugar and let it caramelize slightly. Add tomatoes, peppers and jalapeño and set the temperature a little lower. Add all other ingredients except for the xanthan gum and simmer for about 10 minutes. Finally, add a little xanthan gum, stirring constantly, until the desired consistency is reached.
Caution: Xanthan gum swells up, so use it sparingly first and check after 10 minutes whether more is needed.