meggeth,
it's a really good question.
one thing that really sticks out for me in the dishes i cook often and feel have no improvement is that they taste so different yet have the same basic ingredients. it really is magic.
i think it's purely down to us not knowing the full recipe. i have what i call recipe refinement as a top priority - to make the same dish over and over during a weeks curry cooking and compare to the BIR equivalent. there is still much to do.
i use admins jalfrezi. i like the ashoka bhuna but it's not right. i've never got rogan josh right.
the future is our only hope - the more people trying to crack the remainder of the jig saw the better.