i must stress that my hands-on experiences are only of one pakistani-run scottish BIR, and i've found they use similar methods to the glasgow recipes (re indian takeaway recipe book by alex wilkie aka bb1 aka bigboaby aka fred45) from a while back, if not the same ingredients for everything. the most important is that, like the glasgow recipes, the base is a finished sauce of a thicker consistency and no mix powder is used in the final dishes. unfortunately they don't use the same ingredients, as i never once saw turmeric either being used or stocked, and when i enquired about garam masala (do they make it or buy it in) they don't use a premix, they just use the spices seperately (cassia bark, black cardamom, cumin seeds, salt)