Calling all San Diego area Chowhounds! Does anyone know the recipe for Board & Brew sauce?

I'm new to Chowhound and I heard this would be the best place to come for help figuring out their recipe.

First, has anyone been to Board & Brew? There are a few from San Clemente, CA to San Diego, CA. I don't know if this is the right place to post this, but I'm hoping you all can help.

Second, if you've been there, you have definitely had their sweet and sour sauce. It's amazing.

Does anyone know the recipe? How would I imitate their delicious sauce? Any help is greatly appreciated!

I attached a photo of the sauce.

Thanks!