Thank you for the warm welcome. I feel that "special ingredients/tricks" on their own might not make a discernible difference i.e. using seasoned oil instead of regular oil, but with enough alterations, i.e. seasoned oil, aluminium pan, and onion paste in one dish, perhaps they may. Which of these condiments work together, and in what way, remains unknown to me. It's very time-consuming to test properly (making one or two adjustments at a time and holding every other variable equal: the base gravy, spice mix, tomato paste, seasoned oil, onion paste, etc., the quantities of each, etc.) but I'm curious if anyone has taken the time to do it. It seems like there's just far too much to adjust for unless you're willing to put an inordinate amount of time into cranking out dozens of base gravies, spice mixes, etc. (which I shamelessly am, just the prospect seems overwhelming at times). I think they'd have to be made right after each other, too, since it can be difficult to precisely recall the flavor of a dish. I realize people may find this sort of pedantry rather galling, but that's just how I am.
I've also noticed people speak of that "missing 5%" and, honestly, I'd love for someone to elaborate on what is meant by that. If I order a curry from my local takeaway, it doesn't taste like my curry, yes, but that's true of nearly every curry that uses different recipes/ingredients/techniques. Another point is that people who mention that "elusive BIR taste" order from different restaurants in different regions. How are we certain that everyone has the same meaning of "the missing 5%" in mind? Is there a specific description of that taste? If so, I apologize for the oversight.
One more thing -- on the subject of curry/madras powders (I almost exclusively make madras curries), does anyone have a recommendation? I bought the rajah mild madras powder and found it much too pungent. I prefer the smell of the "Old India" brand that's available on Amazon, but not in supermarkets. If anyone has tried rajah, and knows of a brand that has a milder, more pleasant smell, then I'd love to know about it.