I have seen the chefs with the curry gravy and I really believe the preparation to be simple.
I can usually tell a difference between home made and bought curry.
I think that is down to the freshness of the curry base and the quantity it is made in.
The pans they use contain probably six times more than I would cook.
They must use 40 or 50 onions at one go!
I saw one chef adding the curry powder to the boiled onion mix.
He was using a massive spoon.
He must have put in about four small packs worth (3 oz packs) into it.
I reckon if you scaled up the amounts we have talked about to make curry gravy, and cooked it for a total of six or seven hours (because they keep it warmed up in the evening)
you would get it exact.
I have noticed also that when one of my kids buys a curry on a Sunday it has a different "fresh" flavour.
That flavour is the same as I can make.
I have been told that the gravy is made up on Sundays and Thurdays in two of the restaurants near me.
I tried using three day old gravy and it is different.
It has a "dirtier more spicy" taste.
In my opinion it improves it greatly.
When you cook a curry next do extra portions and freeze some.
It will taste better to you when you thaw it out.
Cooking with spices messes up your sensitivity of taste.