Place the tomatoes, sugar, corn syrup, vinegar, allspice, peppercorns, garlic, onions, cinnamon stick, ginger, star anise and a pinch salt in a stockpot set over medium heat. Bring to a boil, and then lower to a light simmer. Use a potato masher or wooden spoon to mash down and break up the tomatoes as the mixture heats up. Cover and simmer over low heat for 45 minutes, stirring occasionally.
Uncover and cook to evaporate and thicken the sauce while stirring occasionally, 45 minutes more. Remove and discard the cinnamon stick and star anise pod.
Using an immersion blender or a stand blender, blend until smooth. Pour into an airtight container and refrigerate until cool, overnight. Taste and, if needed, add 1/2 teaspoon vinegar at a time to balance the sweetness.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.
This recipe has been updated and may differ from what was originally published or broadcast.