Es Kopi Susu

Why this works

Gula aren is sap from the sugar palm, Arenga pinnata, boiled down until it sets. Unlike refined sugar it keeps everything else that was in the sap, including minerals and compounds formed during the long boiling, which give it a smoky, earthy caramel flavour. That flavour is the reason the drink exists. It reads as more complex and less sweet than the same weight of white sugar, so the drink tastes rich rather than sugary.

The pinch of salt pulls the same trick it does in salted caramel. It suppresses bitterness and makes the caramel notes stand out more. Pandan adds a soft vanilla and grassy note that is very Indonesian and works beautifully with milk.

Building it in layers is partly for the look and partly practical. The syrup is dense and settles at the bottom, the milk sits in the middle, and the espresso floats briefly on top before marbling down. It is stirred before drinking, but the layers make the drink instantly recognisable in a takeaway cup, which mattered to the businesses that made it famous.

Es kopi susu, iced coffee with milk, has existed in Indonesia for a long time. The palm sugar version became a national craze in the late 2010s, when a wave of grab-and-go coffee chains, Kopi Kenangan among the best known, began selling it cheaply through motorbike delivery apps. It turned millions of people who had drunk instant coffee into daily buyers of espresso drinks, using Indonesian robusta and arabica, and a domestic sugar.

Variations

• With condensed milk: a tablespoon of condensed milk with the palm sugar, which makes it richer and sweeter.
• With oat milk: oat milk and palm sugar are a particularly good match.
• Kopi susu panas: the hot version, with steamed milk.
• With a moka pot: 60 ml of strong moka coffee works perfectly well in place of espresso.