Many years ago I watched a curry-house chef knock-up a Madras for me (it may have been a Vindaloo though, I can't quite remember). This was in the Gatwick Tandoori, Ifield Crawley, now called the 'Zari'.
He did not use any chopped onion, garlic, ginger or tomarto puree. I would think that chopped onion would be essential in something like a Bhuna, and probably also the garlic, ginger and tomarto puree, if there is not enough in the oringinal base. I would not have thought it necessary in a madras, but then I haven't tried it so who knows!
I do remember he included a 'shake' (and no more) of Lee & Perrins Worchester sauce. Before he started cooking, he selected a frying pan and swirled it round with just a little oil. I remember being suprised at this because the finished dish was quite oily. This leads me to suspect that in that esatablishment at least, they never bothered to reclaim oil from the finished base, the extra oil present at the end having come from the base itself.
My method is based on his, plus certain additions I've learnt from else where (including this site!). This feeds 2 hungery adults:
I heat 3tbs oil, fry a chopped chillie, and sometimes a small pinch dried curry leaves (not typically used in BIR as far as I can see), when the seeds from the chillie start to darken I add one ladle of base (my bases fall into the thin soup type catagory) and immediately add spices: 4 lev tps Bruce Edwards 'type 2 ' spice mix (his later type containing some commerical 'curry-powder'); 1/4 lev tps pre ground dried methi leaf (I grind a whole box full after I buy it in a spice grinder); 1/2 lev tps salt; 1 lev tps brown sugar; and chillie podwer to taste.
The intial ladle of base acts like making up a paste with the spices and water, it keeps the temperature from climbing TOO fast and burniung the spices. This is something the chef did when I watched him. I cook on high heat for about a minute 'till I get the 'toffee' smell, then add the chicken (I don't bother to pre-cook this as it only takes 10 mins to cook from fresh), I cook for a minute or to, then add the rest of the base (I use 400ml in total), I also add 1/4 tps Worchester Sauce and 3 or 4 tbs of the juice from a tin of plum tomartos, or the tomartos blended with their juice. I find this gives a curry-house style sourness, much more BIR-like than lemon juice / lime juice / tamarind puree or vinegar, all of which I've tried at some stage! I cook for ten mins or so 'till the oil floats, and the pan contents have reduced to the correct consistancy, then add chopped corriander and serve!
Gona have it tonight actually!