I have seen the whole process from start to finish. Around 13 years ago, as the guest of a friendly chef, I spent several sessions in the kitchen of a Take-Away. [ Including midnight to 4 am one Friday as they prepared for the weekend.] What I saw agrees in virtually every detail with Curry House Cookery, which is why I have said that everything we need is already on this site. The coincidence is too great for anything to be very wrong.
I can produce a whole range of curries that have convinced everytone I have given them to, BUT I CAN TELL THE DIFFERENCE. I think my curries are as good as those from most restaurants - they just lack the restaurant smell/ flavour. I have been trying for years to produce this, and have eliminatrd most things. I believe the base sauce is non critical. I have obtained a sample from a restaurant that made no difference to my curries. I have cooked sauce in a 10 litre pot to make sure it isn't quantity. I have bought a 25 litre drum of oil from an Asian grocer - no difference.
I know that my methods, in the hands of a BIR chef can produce a first rate curry, so what am I doing wrong? I had settled into a[ pleasant] rut with my curries, but this discussion got me thinking again. I think the answer lies in the end process, the method of fryin the spices, maybe.something the restaurant chef does automatically, and we dont notice. I have some ideas in this department, so I'll just keep trying, and report back.