Indian recipes are full of sensory instructions rather than clock times, which reads as vagueness to cooks trained on American recipe conventions. The cues are actually the more accurate measurement.
Sound reports temperature indirectly
Mustard seeds pop when the water inside them turns to steam and bursts the seed coat, which happens within a narrow temperature range.
The crackle is therefore a thermometer reading delivered audibly, and it is unaffected by pan thickness, burner output or the amount of oil used.
A written time would have to assume all of those, which is why the instruction is stated as a sound instead of a duration.
Aroma marks a chemical transition
Cook until fragrant describes the moment volatile compounds start leaving the spice in quantity, which is the point at which they enter the fat and the dish.
A few seconds later those compounds begin to break down and bitter notes develop, so the window is short and the aroma is what marks its opening.
No clock can locate that moment across different stoves, spice ages and pan temperatures, but a nose in the kitchen locates it every time.
Visual cues track water content
The instruction to cook until the oil separates is a statement about moisture. Fat visibly pooling at the edges means enough water has evaporated for the mixture to break.
That state matters because browning cannot proceed while water is present, so the separation marks the start of a different chemical stage.
Onions turning from translucent to golden works the same way, describing a stage of sugar browning rather than an elapsed period.
Why American recipes read differently
Published US recipes lean on times and temperatures because they are testing in standardized kitchens and writing for readers who want the process bounded.
That works well for oven baking, where the environment is controlled, and works poorly for stovetop cooking, where output varies between households.
The best compromise is what many modern recipe writers now do: give the cue first and a rough time in parentheses as reassurance rather than instruction.
Learning the cues faster
Cooking a step deliberately too far once, and noticing what burnt cumin smells like, teaches the boundary more effectively than any number of successful attempts.
Measuring all spices into a small bowl before heating the fat removes the scramble that causes most timing failures during a tempering.
Once the cues are learned they transfer across dishes and cuisines, which is why they are worth more than the recipe that taught them.