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Kopi joss

Sweet black coffee with a glowing lump of charcoal dropped into the glass. A Yogyakarta street speciality, and exactly as odd as it sounds.

Kopi joss is sweet black coffee with a glowing ember of charcoal dropped into the glass. It comes from Yogyakarta in central Java, where street stalls have served it since the 1960s.

The name is onomatopoeic — the joss is the hiss when the charcoal hits the coffee.

What it does

The charcoal is glowing hardwood, briefly quenched. It fizzes violently, then sits at the bottom.

The claimed effect is that it reduces acidity — which is chemically plausible, since ash is alkaline and would neutralise some acid. Vendors also claim it settles the stomach, which is folklore.

What it definitely does is add a smoky note and a distinct texture from the fine ash.

Is it safe

Charcoal from hardwood is essentially activated carbon, which is consumed medicinally. The practical concerns are what the charcoal was made from and whether anything was used to light it.

Street vendors use plain hardwood embers from a brazier. Do not attempt this with barbecue briquettes, which contain binders and accelerants.

Making one

Kopi tubruk — fine coffee and sugar in a glass, boiling water poured on — then a small ember of plain hardwood charcoal from a fire, tonged in.

The honest note

It is a spectacle as much as a drink, and it is a genuine local tradition rather than a tourist invention.

What you need to make it

The equipment this actually requires — not a shopping list, the shortest route to doing it properly.

  • The original, still right Moka pots

    Bialetti Moka Express 3-cup

    Aluminium · 130 ml · not induction

    Ninety years old, sold by the million, and misused by almost everyone who owns one. Brewed properly — low heat, pre-boiled water, off the hob at the first gurgle — it is one of the great cheap coffees.

    Best for: One or two strong cups on a gas or electric hob, at almost no cost.

    8.0/10

    ≈ $35 / £25 / 25 €

  • Cheapest honest espresso Espresso machines

    De'Longhi Dedica Style EC685

    51 mm portafilter · 15 cm wide · pressurised baskets

    Fifteen centimetres wide, heats in forty seconds, and makes a decent drink for under 200. It ships with pressurised baskets that fake crema from any grind — which is exactly why it works for beginners and why it stalls after a year.

    Best for: A tiny kitchen, a first espresso machine, or a second machine for an office.

    7.2/10

    ≈ $200 / £170 / 180 €