A bombilla — the metal straw with a filter at its lower end that makes traditional maté drinking possible. It is a drinking vessel and a strainer in one object, and it is one of those tools that turns out to have been solved properly a very long time ago.
What it is for
Traditional maté is not brewed and strained like tea. The loose leaf goes straight into a gourd or cup, hot water is poured over it, and the drink is taken through the bombilla — whose perforated or spring-wound base holds back the leaf while letting the liquid through. The leaf stays in the vessel the whole time and is topped up with fresh water again and again through a session, which is why maté is a slow, sociable drink rather than a single cup.
You do not need a gourd. A sturdy mug works perfectly well and is how most people outside South America drink it.
Using it
Fill the cup about half to two-thirds with loose maté, tilt it so the leaf banks up on one side, and pour a little cool water into the hollow first — this protects the leaf from the heat to come. Insert the bombilla into the damp hollow and do not stir with it: moving it around drives fine dust into the filter and blocks it. Then add water at about 80 °C, never boiling.
Top up as you drink. The same leaf will take many refills before it gives out.
Cleaning — the part that matters
A bombilla clogs if it is not rinsed straight away. Run hot water through it immediately after use, from both ends, and shake it dry. Every week or two, soak it in hot water with a spoonful of bicarbonate of soda, then flush it through again; a pipe cleaner or a thin brush deals with anything stubborn.
Left dirty, tannin and leaf dust set inside the tube and become very difficult to shift. Ten seconds under the tap prevents an hour of scraping.
Note
Metal conducts heat. The straw gets hot when the drink is hot, which is a further good reason to let maté cool below about 65 °C before drinking it.