Plum BBQ sauce

Ingredients
10 whole allspice berries
1 cinnamon stick
1/2 tsp whole coriander seeds
10 whole cloves
2 Tbsp olive oil
2 onions, peeled and chopped
6 cloves garlic, peeled and chopped
1.8kg plums, pitted and roughly chopped
1/2 cup apple-cider vinegar
3/4 cup brown sugar, packed
1 Tbsp molasses, golden syrup or honey
1 tsp dry mustard
1/2 tsp dried chili flakes, or 2 fresh hot chili diced
1 Tbsp salt, or to taste
Optional
A generous splash of Worcestershire, fish or soy sauce
3Tbsp Chinese black vinegar

Method
In a large, heavy, nonreactive pot over medium heat, warm the olive oil. Add onions and cook until golden and just beginning to brown. Add garlic and cook, stirring, for another minute or two.
Add plums and cook, stirring frequently, until fruit has collapsed and softened into a chunky puree. Add vinegar, sugar, molasses, mustard, hot peppers, and salt. Put whole spices in a cheesecloth/spice bag and drop into the plum mixture. Add about a tablespoon of Worcestershire or other sauce, if desired.
Bring mixture to a simmer, stirring frequently. Reduce heat to low, partially cover and cook, stirring often, until mixture is thick and smooth. Be careful not to let mixture scorch or stick to the pan. Taste for seasoning, adjusting with more vinegar, sugar, molasses, or salt as needed. Remove and discard spice bag.
Pour into clean glass jars. Let cool, then refrigerate.

Chook's note: add more chili if you like it hot. These sorts of recipes are very forgiving so knock yourself out adding other aromatics or tweaking quantities. It's all about personal taste.
I made half quantity and ended up with 2 bottles of sauce (I sterilised the bottles in the dishwasher -so much easier).
I have still to try out a couple of other BBQ sauce recipes.  Watch this space!

Thank you Bay Area Bites for the idea.