Make a spice sachet from a double or triple layer of cheesecloth (a square 3” – 4”). Place the piece of cinnamon stick, star anise pod, bay leaf, mustard seed, whole cloves, peppercorns, and allspice in the center of the cheesecloth and gather up the sides to form a little sachet. Tie tightly with string and set aside.

Combine the chopped tomatoes, rhubarb, celery, shallot, garlic cloves, apple cider vinegar, and spice sachet into a medium-sized stockpot. Bring mixture to a boil over medium-high heat, stirring occasionally. Reduce heat to medium-low and cook, uncovered for about 40-45 minutes, stirring frequently. Do not boil.

Remove and discard spice sachet. Cool mixture for approximately 20 minutes then purée in food processor or blender. Strain mixture through mesh sieve to remove any solids that may remain. Return strained mixture to a clean stock pot and add the brown sugar, liquid honey, and sea salt. Cook slowly, uncovered, over low heat for 30-40 minutes or until mixture is reduced to about a cup and thickened. Stir often as the ketchup cooks and also as it cools to help it to thicken.

Store in tightly covered jar in refrigerator for up to 1 week.