Fixation preserves rather than creates
Green tea’s character comes from what does not happen to it. Heating the leaf shortly after picking denatures the enzymes that would brown it, so the fresh compounds present in the living leaf survive into the cup instead of being converted. Grassy, marine and vegetal notes are the leaf’s own character kept rather than a flavour added.
Steam and pan give different results
This is the largest single variable in green tea. Steaming makes no contact with hot metal, so nothing toasts — the marine and seaweed-adjacent character of sencha and gyokuro survives intact. Pan-firing tumbles the leaf against a hot wok, and the surface browning contributes chestnut and roasted-grain notes that are inseparable from the method. Longjing and sencha taste unalike for this reason far more than for any difference in the plants.
Shading pushes it towards savoury
Covering the bushes for a week or more before picking shifts the leaf’s composition towards the amino acids associated with savoury depth and away from those associated with astringency. Gyokuro, kabusecha and matcha are the result, and they read as thick and umami-rich rather than grassy — the same category, moved a long way by a decision made in the field rather than the factory.
When grassy becomes harsh
The compounds carrying astringency and bitterness extract far more readily in hot water than those carrying sweetness and savoury depth. Boiling water on a delicate green tea therefore extracts the harsh fraction efficiently and the pleasant one poorly, giving a cup that is thin and bitter at once. If green tea has consistently tasted unpleasant to you, the water was almost certainly too hot.