We tried Fat Matt's (Atlanta) the other day and you're right - it IS way above average for around here. Jack and I split a pulled pork sandwich (fine chop mixed with their sauce) and a half-rack of ribs. Both were very good and it's a place I'd go back to. Sauce was good too. Brisket is not on the menu, but chicken is.
I couldn't help myself. I bought a bottle of their sauce. We all need to try to figure out the formula! Here are the ingredients:
Tomato puree, vinegar, corn syrup, refiners syrup, mustard seed, salt, condensed natural hickory smoke, molasses, spices, garlic powder, caramel flavor, caramel color, aged peppers, water, sugar, natural flavors, onions, white pepper, black pepper, turmeric, anchovies, tamarinds, crushed red peppers, and sodium benzoate as a preservative.
Nutrition: 2 tablespoons = 40 calories, 0g fat, sodium 350mg, carbs 9g, very little of anything else.
An ingredient or two might only be available commercially. I'm not familiar with refiner's syrup. Might it be an uncommon name for corn syrup or something we know under another name?
I think KingArthurFlour.com carries caramel flavor and color, but why not just caramelize some sugar?
I'm assuming that "aged peppers" means dried peppers such as ancho, etc.
The bottled sauce tastes a little heavy on the smoke. They claim it's the same sauce as they serve with their pork, chicken, and ribs. I wish I'd saved some of the sauce we got with our food to compare with the bottled sauce.