The 3 ingredients we need are:
1. Tea: any tea can be prepared with the gongfu cha method. Of course, fine Chinese whole leave teas are perfect for gongfu cha, but you could even use a plain tea bag! The goal of gongfu cha is, for a given tea, to find the best parameters to brew the best possible cup of tea with it.
2. Water: Tea is 99% water. So you better choose your water very carefully. A good way to start learning about tea is to blind test several waters (mineral, purified, tap...) you consider using for your tea. Find out by yourself which one slips most easily down your mouth and has a mellow, but neutral taste.
3. Fire: Heat lets the leaves release their flavors faster. A 100 degree Celcius brewed tea will release twice as many molecules as when brewed at 80 degrees C. That's the reason why Lu yu and Teaparker recommend to always use water that has reached the boiling point for a short period of time. Best is to cook the water at medium speed in order to catch the right moment, when the bubbles have the size of crab eyes. An overboiled water will taste 'old' and loose its freshness. If this should happen, add fresh water to the overcooked water and boil more carefully again.
23 hours ago