3 ideas
The Western word "curry", and the premixed curry powder that came with it, flattens a family of distinct regional cuisines into one generic yellow sauce. Jaffrey argues that no Indian cook uses a single all-purpose spice blend. Each dish takes its own combination and proportion of spices, and that combination is what gives the dish its identity.
The same spice gives different flavors depending on how it is handled. Whole seeds popped in hot oil (a tempering, or tarka), dry-roasted and ground, or cooked as a paste each produce a distinct taste. Indian cooking therefore depends as much on the order and method of adding spices as on which spices are in the pot.
Jaffrey learned to cook away from home: while studying in London, missing her mother's Delhi food, she worked out dishes from recipes her mother sent in letters. The book draws largely on that family kitchen.