Stubb's Original BBQ sauce

The following recipe is my attempt to replicate the taste of a commercial product. This time, it's Stubb's Original BBQ sauce.

Label contents
"Water, Tomato Paste, Sugar, Distilled Vinegar, Molasses, Corn Starch, Tapioca Dextrin, Salt, Brown Sugar, Spices, Contains Less than 0.5% of: *Onion, Paprika, *Garlic, Chili Powder, Natural Smoke Flavor, Xanthan Gum, Guar Gum, Citric Acid, Corn Syrup, Tamarind, Natural Flavors. *Dried"
16 oz tomato purée
1/4 cup white sugar
1/4 cup white vinegar
1 Tbl molasses
1 Tsp brown sugar
1/4 Tsp onion powder
1/4 Tsp sweet Hungarian paprika
1/4 Tsp garlic powder
1/2 Tsp chili powder
1/2 Tbl dilute liquid smoke
1/4 Tsp cayenne pepper
1/8 Tsp celery seed
black pepper
Combine the above ingredients in a non-reactive sauce pan. Adjust for salt, and add a fair amount of pepper. Bring the contents of the pan to a boil, cut the heat and simmer slowly until the sauce is slightly thick.
Re-hydrated tomato paste can be substituted for tomato puree. Place a level 2/3 cup of tomato paste into a 2 cup Pyrex measuring glass, add enough water to bring the liquid to 16 oz, then use a stick blendor to combine. "dilute liquid smoke" refers to the amount of water in the product. If the label indicates that water is first ingredient, it is "dilute liquid smoke".

To make chili powder, process 1/4 Tsp cumin seeds and 6-8 de-seeded chile d'Arbol pods into a coffee grinder. Process the mix until very fine.