UK people- brown sauce replacement

Options
I guess this mainly for UK people as i dont think many other nations have brown sauce ( HP/Daddies). Its basically a smooth chutney.

Im looking for a replacement for use in recipes. I use it in my sausage casserole. Id like to replace it with somthing ( or ingredients) that are not sugary as im hypoglycaemic. I also dont do artificial sweeteners or stevia.

Im thinking vinegar, tomato puree, maybe grated apple? Any suggestions would be appreciated.

Replies