Sorry George, as much as I normally respect and agree with your opinion, on this occasion I have to disagee with you (a little). A BIR curry is not cooked or despatched in quanities much above two portions. Heat and maintaining of, is - in my opinion - essential to the cooking process, albeit somewhat a hit or miss process, domestically. There is no way that a domestic burner is high enough in power output to cater for more than 4 servings cooked in the BIR fashion. I suppose this goes back to another thread about what temperature spices should be cooked at ........... or not?
I can't be sure, of course, because I've never tried cooking industrial scale quantities to feed 100 people. I would expect the main challenge to be logistics, purely in terms of the volumes involved. Schools and other institutions cook large quantities, so it's nothing new.
Base sauce - no problem, surely. BIRs prepare large volumes. Indeed some people say smaller volumes 'don't work'. Cook in 1, 2 or 3 batches.
Pilau rice - I don't see how this will be very difficult either. Again some/most BIRs prepare large volumes of pilau rice in advance and only reheat it later in smaller portion sizes. If a table of 8 all order pilau rice, there's no way they'll cook it 8 times!
Korma - I found that low heat works fine. High heat is neither necessary nor desirable, so I would expect high volumes of korma to turn out fine, as well.
Madras and similar dishes - the least certain outcome - since a high heat, stir fry type approach is normally used. I still reckon that batches of around 2.5 litres would be perfectly manageable (cooked in a larger pan) and 90% as good, if not 100% as good as a 0.5 litre normal-sized portion (cooked in a smaller pan), over the same domestic hob.
I also wonder what happens in a BIR if half, say, my table of 8 (above) all order the same dish - like CTM - and another 3 orders for the same dish (CTM) come in at the same time from another table. Total 7 portions of CTM required. Would they really cook it 7 times, one after the other? I find it difficult to believe.
Regards
George