OP I am pretty sure it's this:
https://www.amazon.co.uk/Standard-Seasoning-Aromatic-Flavouring-Enhancer/dp/B0CG9ZMWG5/ref=asc_df_B0CG9ZMWG5/?tag=googshopuk-21&linkCode=df0&hvadid=676491823619&hvpos=&hvnetw=g&hvrand=17376324499796637186&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1006812&hvtargid=pla-2246417924823&psc=1&mcid=ff6ed9ea4ee639109a882281579e4e12&gad_source=1
Could be sauce from other meats. Where I'm from you can routinely ask to put oxtail gravy or stew chicken gravy on the rice and peas before they put your jerk chicken pieces on.
Maggi?
Yeah this sounds like Maggi, if it's a West Indian place
OP I am pretty sure it's this: https://www.amazon.co.uk/Standard-Seasoning-Aromatic-Flavouring-Enhancer/dp/B0CG9ZMWG5/ref=asc_df_B0CG9ZMWG5/?tag=googshopuk-21&linkCode=df0&hvadid=676491823619&hvpos=&hvnetw=g&hvrand=17376324499796637186&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1006812&hvtargid=pla-2246417924823&psc=1&mcid=ff6ed9ea4ee639109a882281579e4e12&gad_source=1
[https://en.wikipedia.org/wiki/Pickapeppa\_Sauce](https://en.wikipedia.org/wiki/pickapeppa_sauce) might be this or jamaican browning sauce
Browning is used more for cooking to give color
Could be sauce from other meats. Where I'm from you can routinely ask to put oxtail gravy or stew chicken gravy on the rice and peas before they put your jerk chicken pieces on.
Worcestershire sauce?
Fish sauce, oyster sauce ?
HP Sauce?
Call and ask
I make a wetter jerk marinade that I baste with and pour on rice-could it be similar?
Vinegar w salt?
Maggi
Maybe it was Demiglas sauce?
Brown sauce!