It was always possible that I misunderstood pete's original post and I've said that previously. As far as I'm now concerned, pete answered my initial question satisfactorily here.
I'm sorry if that was misleading
No, I meant after countless recipes, I don't believe you can make a restaurant curry base at home.
I think the result is only obtainable by using seasoned bhajee oil and cooking on a very large scale
The aroma of a sample base, when heated, is the BIR aroma
You can't get that, with a home made base
I now believe he originally used the word "secret" in a general and broad sense, which was not intended to be interpreted literally. He may have said the key to success is in the Base Gravy. I can understand how his claim of it "not being on this or any other site" is in direct reference to exact base gravy recipes on this or other sites. I'm fine with his explanation here.
yes that is what I meant
I started getting into the takeaway kitchens about 13 years back
and I have seen and even helped to make the curry gravy in takeaways
the seasoned oil is normally added after boiling up the onions/tomatoes and peppers for an hour and a half
the oil is not manky or horrible, or in any way bad tasting
I have actually tasted a little bit it on it's own
it's slightly hot and there is a "fried" flavour about it
pretty dull really
nothing exceptional
it's always filtered anyway
so there are no burnt bits in it
But when the oil is added,,to the boiled onions, within 5 minutes, the BIR aroma just hits you, and doesn't disappear
It's just there really strong
Even after blending
After it's blended
the gravy was always boiled again until the oil rose to the top
Then you let the gravy cool down a bit
Maybe an hour
Scoop off all the oil you could, for starting off the curries
this oil always seems to be held in old tomato puree cans
there is normally one on the cooker full of this oil
what can I say?
When I add fresh oil to my boiled onions, at home, I don't get the aroma
ANYTHING used with proper BIR gravy, has the BIR taste and aroma
even if you made a curry with no extra spices or garlic ginger or any main ingredient, which they sometimes do
I've seen people have chips and curry sauce made like that, and it's still BIR tasting
I also think cooking the base very large helps too
These are just my thoughts, perhaps I'm wrong
But I hit a wall on my cooking over 10 years ago which I just can't get through
and these are my conclusions