Add the onion and garlic to a small saucepan. Saute on medium for 5 minutes until aromatic.
Add all additional ingredients and stir well.
Bring to the boil, then reduce to medium-low and simmer for 20 minutes.
Take the pan off the heat and allow to cool.
Strain the sauce into a bowl, discarding the solids.
Video
Notes
If you don't want to use ketchup, or can't find a no-sugar added version, you can substitute with 1/2 cup tomato puree mixed with 1/2 cup water.
Any type of liquid smoke works, but I particularly like hickory.
The servings size is just about 1.5 tbsp for 2 grams of carbs.
If you don't want to discard the onions, you can finally chop them and keep them int the sauce. If you want a smooth sauce, just puree it in the blender.
The sauce can be stored in the refrigerator for up to a week.
The information shown is an estimate provided by an online nutrition calculator. It should not be considered a substitute for a professional nutritionist’s advice.