Marijuana sales once helped fund the 30-year war waged by separatist rebels and when they descended from their mountain strongholds after the 2005 peace deal, the plantations remained.

To this day, two lucrative cash crops – coffee and "ganja" – provide a healthy income in Aceh's rural hinterland.

In a pungent smoke haze at a secret location in the capital, Banda Aceh, an enterprising group of young stoners is combining the two into what could perhaps be viewed as the essence of Aceh.

Syahrul* and his two buddies take 250 grams of rich, dark Arabica beans grown in Gayo and mix in 10 grams of finest, field-grown organic mull, then, squatting on the floor of their tiny room, they grind it all together.

The end product is packaged like normal coffee and named with a wink after the infamous civet cat-excreted Coffee Luwak: they call it "Coffee Lawak", which literally means, "Coffee Buffoonery".

"Coffee normally makes you feel alert and wakes you up," Syahrul says. "This coffee doesn't do that."

They sell their special mix to cafes around Banda Aceh where you can buy a cup for 70c – compared with 30c for a normal espresso – if you know what to ask for. And it's delicious.

Even better, the three boys – all Muslims who pray – insist their brew is guilt free, because it's permitted under Islamic law. Their home-made religious ruling is based on the fact that nowhere in the Holy Koran is ganja mentioned. They do concede it may not strictly be halal – meaning good – but they'd be content with makrooh, or "doubtful". It's the same grey area that allows millions of Muslims to smoke cigarettes.

Wrong, Banda Aceh's sharia police enforcement chief Evendi Latif tells Fairfax Media: "Any substance with an intoxicating effect is haram".

But it's not mentioned in the Koran, we insist.

"That's just an excuse they use to smoke ganja."

The Acehnese have a long tradition of mixing weed into their cooking. Its value as a herbal flavour enhancer made the best goat curry in the land, so they say, and, if you know where to go, you can still sample it. That too, sadly, is haram, Latif intones.

Despite these fatwas, Aceh's drug addiction remains profound. Acehnese are often caught shipping ganja by the tonne out to the rest of the country and, shortly after the new year, police demolished 800,000 plants on a property four hours' walk from the nearest road. Some darkly suggest that these raids are merely designed to protect a much bigger and more lucrative business run by the police themselves.

Aceh is also the gateway between Malaysia's gigantic ice manufacturing factories and the growing market for the drug in Indonesia, where it's called sabu sabu. A police officer was arrested last October trying to smuggle a kilo of that into the country.

The latter trade distresses Syahrul and his buddies profoundly. They say sabu sabu pushers are targeting high school students all over Aceh with cheap product to get them hooked.

"We don't like that. It's synthetic and no good," Syahrul says.

"We like this," says his friend Sofyan*, indicating the gigantic, cone-shaped joint smouldering between his fingers. "We're just nature lovers at heart."

*Not their real names