From my time spent in a bir kitchen, the chef said learning madras is the key to learning most other dishes (bhuna, rogan josh, balti, vindallo). Therefore if you can derive a great madras from the base, then it stands to reason the base must be spot on. I do agree though, that the korma is also essential. oddly, i have tried nearly all bir dishes accept korma. must order one, and get a demo next visit to my local ta. My local TA manages to do without the onion paste, and other fancy extras. They still produce great curries with just a base and literally garlic puree, spice mix, chilly, coriander, salt, chopped onion. Their base is fantastic. He is a bit reluctant to give me the full recipe. it would be such a great addition to this site. His spice mix is available in recipies section 'DD spice mix'