hi pp try the Natco website it gives the original recipe which had been ripped off. the so called "secret ingredient" is now no longer used elsewhere. but opinions varied on the results again there is regional differences to take into consideration. but for many it was not the answer. imho there is no secret magic ingredient and a more than happy that i can reproduce Rajver chicken vindaloo/madras/chilli masala/korma( have made for my friend and they love it, not chilli heads) and phall(the DB). i no longer measure my ingredients but do it so regularly and i lay all my ingredients out in their pots and use my chefs spoon same method every time. my recipe for chicken tikka is adapted from the many on this site and my girls love it and my friends will be enjoying it tomorrow night i have 2 kilos marinating in my refridgerator by then it will have been 48hours yummy!
am also cooking a large korma possibly with some of the tikka and a vindaloo, gits onion bhajis and poppadums fresh( will save the oil for next base) and may have talked myself into making an aloo gobi as well oh and don't forget the mint sauce!
will let you all know how it goes

regards
gary