BBQ chow mein recipe from ENGLAND?

Hi,

I’m looking for a very specific BBQ sauce recipe. I’ve tried about 10 and none of them are right so far.

The sauce I’m looking for comes from Stafford in the UK from a chinese take away called “Peony Garden”. It comes on the Special Chow Mein. “Wongs” in Newcastle-under-lyme use it as well on their spare ribs.

Do they buy this sauce pre packaged or do they make it themselves?

If anyone knows how to make this sauce PLEASE give me the recipe! (or if it’s store bought, let me know the name and where I could possibly find it!)

thanks!!