hi..i think ive cracked it , i have made two curry bases, 1 from mamta gupta`s  and the other from kris dillons.   In both i added 3/4 of a teaspoon of aesofatida while making the base...which gives the sweet taste ..aso i use methi leaves but the most interesting part was when i tried to make a curry from the base i put a sliced chilli along with a teaspoon of chilli powder into hot oil and stirred quickly....wow the strong smell of burning chilli so i added the base sauce a bit at a time stirring..well rubing  the large chefspoon off the bottom of the pan as i went .the endresultwas the smell and tate with red looking oil round the edges.I dont know how long i can burn chilli without wasting it but i feel really heating chilli like this is the answer to the secret...along with aesofatida a small drop of yoghurt too near the end. another thing i found was making mince curry i always ended with a fatty tasting mince when i followed any recipe well what i do now is dry fry mince for a while and empty out all liquid before adding to curry sauce..i hope this helps