Hi NJ,
What a fantastic post, a real gem amongst some of the best cr0 posts'
I too have experimented with a 'concentrate' base gravy but for slightly different reasons to your good self. Mine was purely for space saving reasons, just to keep Mrs Razor off my back, whereas your reason was for finding a suitable use for your slow cooker. It's for a very similar reason, that I've never invested in one, don't think I would get the most from one to be honest.......until now..!
So you have tried and proved this method on a few occasions?, how do you think it compares with your normal base of choice, cooked in the conventional way?
mmmmm, this has got me wondering if a BIR style curry could be cooked in the slow cooker? Obviously, using all the ingredients that you would usually use normally? Nah, can't see it, how would you release the oils out of the spices for a start?
Great post mate, keep up the good work

Ray
