Most of us spend our mornings trying not to get charcoal in our food. In Yogyakarta, Indonesia, they do the exact opposite. They take a piece of burning, red-hot coal from the stove and drop it right into your glass of coffee.
This is Kopi Joss.
When that coal hits the liquid, the whole thing erupts in a hiss of steam and bubbles. It’s easily the most metal way to prepare a beverage. But there’s actually some (pseudo) science behind the madness. The locals say the charcoal neutralizes the acidity of the coffee and binds to some of the caffeine, making it “smoother” and easier on the stomach.
What It’s Actually Like: Despite looking like something you’d find at the bottom of a grill, it doesn’t taste like an ashtray. It has a subtle, earthy smokiness—almost like a roasted marshmallow, minus the sugar. You let the coal sit for a minute, blow off the surface ash, and sip around it.
The Verdict: Is it a bit of a gimmick? Sure. Is it the coolest-looking drink you’ll ever post on Instagram? Absolutely. It’s a reminder that coffee doesn’t always have to be a sterile, lab-grown experience. Sometimes, it’s okay to play with fire.
Kopi Joss Recipe
Ingredients:
- 2-3 tablespoons finely ground dark roast coffee (traditional Javanese coffee preferred)
- 2-3 teaspoons sugar (adjust to taste, or use 1 tablespoon if you like it sweet)
- 1 cup (240 ml) boiling water
- 1 piece of hardwood lump charcoal (size of a large walnut or small golf ball)
- Optional: 1-2 tablespoons sweetened condensed milk
Special Equipment Needed:
- Heat-safe glass (traditional small glass cup or heat-resistant tumbler)
- Metal tongs or chopsticks
- A heat source to burn the charcoal (small charcoal grill, camping stove, or gas burner)
- Small fan or piece of cardboard (to blow ash off the charcoal)
IMPORTANT SAFETY NOTE:
This recipe involves live fire and burning charcoal and is provided for informational purposes only. Do this outdoors or in a very well-ventilated area. Never use chemically-treated briquettes or charcoal with lighter fluid—you need natural hardwood lump charcoal ONLY. If you’re not comfortable handling burning charcoal, just… don’t make this. If you decide to try this recipe, you assume all risks and responsibilities.
Instructions:
1. Prepare the charcoal (This is the tricky part): Light a piece of natural hardwood lump charcoal using your grill, camping stove, or gas burner. You want it glowing red-hot—not just warm, not just smoking, but legitimately on fire and glowing like the eye of Sauron. This takes 10-15 minutes. The charcoal should be about 250°C (480°F).
2. Make the coffee base: While the charcoal is heating, add the ground coffee and sugar to your heat-safe glass. Don’t use your favorite ceramic mug for this—glass is traditional and lets you see the show. If you’re using condensed milk, add it now too.
3. Add boiling water: Pour the boiling water directly over the coffee grounds and sugar. Stir briefly to dissolve the sugar. Let it sit for about 30 seconds—you’re not trying to make perfect pour-over here, you’re making street coffee.
4. Prepare the hot charcoal: Using metal tongs (do NOT use your hands, obviously), carefully lift the red-hot piece of charcoal from your heat source. Gently blow on it or fan it to remove any loose ash or embers. You want the charcoal itself, not a cloud of ash in your coffee.
5. The grand finale: Hold the glowing charcoal over your coffee glass for dramatic effect (this is the Instagram moment). Then drop it directly into the coffee. It will immediately hiss, sizzle, bubble, and steam dramatically—this is the “joss” sound that gives the drink its name. DO NOT lean over the glass when you do this. Hot steam and coffee can splash.
6. Let it settle: Let the charcoal sit in the coffee for 1-2 minutes. It will continue to bubble gently. The charcoal is neutralizing acids and adding a subtle smoky, caramelized flavor.
7. Drink (carefully): You can either fish out the charcoal with a spoon before drinking, or do it the traditional way and just sip around it. The charcoal will sink to the bottom. Some people leave it in the whole time, others remove it after a minute. Your call.
What You Need to Know:
- The right charcoal matters: Traditional Kopi Joss uses charcoal from sambi wood (a hardwood from Kalimantan). You won’t find this in the U.S., but any natural hardwood lump charcoal works—think the kind you’d use for grilling, but NOT Match Light or any kind with additives. Coconut shell charcoal also works. Absolutely DO NOT use regular charcoal briquettes with binders or chemicals.
- Is this safe to drink? Look, Indonesians have been doing this since the 1960s without mass casualties. The charcoal used is essentially activated carbon, which is sold as a health supplement. That said, this is BURNING WOOD you’re dropping into a beverage. Use clean, natural charcoal and don’t do this every day.
- Does it actually neutralize acidity? Activated charcoal is known to absorb compounds, so theoretically yes, it could reduce some of the acidic components in coffee. Whether it does this effectively in the 60 seconds it sits in your cup is… debatable. But locals swear by it for upset stomachs.
- What does it taste like? Not like an ashtray, surprisingly. Most people describe a subtle burnt caramel or toffee note mixed with the coffee. The sugar caramelizes slightly when the hot charcoal hits it. It’s smoky but not overwhelming—think campfire marshmallow, not house fire.
- Where to get it: If you’re in Yogyakarta, go to the string of angkringan (street food stalls) on the north side of Tugu train station. Open around 4pm. One cup costs about 5,000-10,000 IDR (35-70 cents USD). The original stall is Kopi Joss Lik Man.
- Why would anyone do this? According to legend, the inventor (Pak Man) had an upset stomach and thought charcoal might help. He was right—or at least, he started a trend. Now it’s equal parts local tradition, tourist spectacle, and genuinely interesting coffee experience.
Variations & Notes:
Kopi Joss Susu: Add 2 tablespoons sweetened condensed milk before adding the charcoal for a creamier, sweeter version.
Iced Kopi Joss: Yes, this exists. Make the coffee hot with the charcoal, let it cool slightly, then pour over ice. The drama is reduced but it still tastes good.
Can I skip the charcoal? Then it’s just regular Javanese coffee (which is also good). But you lose the whole point. The charcoal is what makes it Kopi Joss.
Alternative if you’re scared of fire: Some cafes outside Indonesia make “charcoal coffee” by adding activated charcoal powder to regular coffee. It’s not the same experience AT ALL—no sizzle, no drama, no fun—but it might give you a similar flavor profile without the fire hazard.