What is a chawan, and does the bowl matter?

Width first. You want enough surface for the whisk to travel without catching the sides, which is what builds the fine foam.

Then a flat-ish base so the powder gathers where the whisk can reach it, and walls thick enough to hold heat without becoming too hot to cradle. A slight inward curve at the rim keeps the tea where it should be as you drink.

Our bowls are Kiyomizu ware, made in Kyoto's Kiyomizu temple district, an area associated with ceramics for centuries and still home to working kilns.

They are made by T. Nishikawa & Co., Inc., founded in Kyoto in 1917 and now run by the founder's granddaughter. Each piece is hand-formed, hand-glazed and hand-painted.

The glazes are layered and iron-rich, and they move in the kiln. They break over edges and pool at the foot, so colour gathers thickly in places and thins to almost nothing elsewhere.

The effect has a name, keshiki, meaning landscape: you read the surface of a bowl the way you would read a view. It cannot be planned exactly, which is the point.

Rinse with warm water and dry it properly. No soaking, no dishwasher, and let it reach room temperature before pouring hot water in.

Warm the bowl first with a splash of hot water poured away before you start. It holds the tea at temperature and is one of those small habits that quietly improves the result.