I've managed to get hold of a few samples of base gravy from different places over the years.The person taking the order normally gives me a funny look but when I explain that I'm a keen amateur BIR cook they're usually quite interested and only too willing to listen and give me a sample of gravy.
Without exception,every sample I've been given has been really thin and
watery.In my early cooking days I made the mistake of leaving my gravy too thin,I thought how can I make a decent curry with thin watery gravy?? However if you cook it for long enough it does indeed thicken on its own in the pan.Don't stir too much,just scrape the sides down now and again.
I reckon he was actually describing how he makes his madras,adding oil and onions.If you cook the curry long enough they will kind of melt away into the sauce.
I've just had a new take-away opened up nearby,the food is excellent and the added bonus is that it's a completely open kitchen.I watched the chef cook my order last night.He had a runny gravy,I'm going to ask him for sample next time.He must have thought it was quite amusing when he was cooking,I had my nose pressed against the window the whole time.He left all of the curries bubbling away for ages,not stirring,just as I do,I'm convinced that you have to cook your curries for ages to get the right flavour.