• 4 tablespoons of ketchup (or 2 tablespoons of concentrated tomato paste)

• 4,5 tablespoons of ketjap manis (thick soy sauce)

• 1 big tablespoon of thick apple syrup

• 2 drams of Dalwhinnie (Winters Gold), or other whisky

• Half a teaspoon of something spicy (I used half a teaspoon piri-piri.)

Take a small pan and put the ketchup, ketjap and Apple syrup in the pan. Turn on the heat on low temperature and stir until all the ingredients are mixed
Add the whisky and stir it with the other ingredients.
Warm the sauce on medium to low hight and make sure it does not boil or gets to a cooking point.

The sauce might smell a bit like vinegar, no worries, that will fade away after a while. Keep heating it until it becomes a thick sauce like structure. Check this by looking on how it drips on the spoon. (Keep in mind it looks thinner then it is while hot.)
On th image you'll see how the sauce starts sticking on the top of the spoon.

Like I mention in the ingredient list; You can use concentrated tomato paste. This will get you a thicker sauce, but I was not a big fan of the flavour coming from that.