In Indonesian, kecap is a phrase which simply means “fermented sauce,” but it has come to be used specifically to refer to soy sauce. There are two major styles of Indonesian soy sauce, kecap manis and kecap asin. Both are widely available from Asian markets, and they are certainly worth experimenting with, because they have unique flavors which are designed to complement Indonesian food to perfection.

Like other soy sauces, kecap is made by fermenting soybeans with salt and other ingredients to create a distinctively flavored liquid. Kecap, incidentally, is probably the fermented sauce which inspired the flavor and name of ketchup; early forms of ketchup were made with an assortment of fermented ingredients, rather than tomatoes. Kecap can be sprinkled onto foods or added to food as it cooks to bring out a desired flavor.

Kecap asin is a salty soy sauce with a relatively mild flavor. If a recipe calls for kecap asin and you have trouble finding it, you can use Japanese usukuchi shoyu or an ordinary light soy sauce. Because kecap asin is naturally very salty, go easy on the salt when you include this sauce in a dish, to ensure that you do not overwhelm consumers with saltiness. Kecap asin can also take a moment to fully develop its flavor in a dish; the best practice is to add a small amount, allow the dish to sit for a moment, taste, and adjust the flavor as needed.

Kecap manis is a truly unique form of soy sauce. It is made with the addition of palm sugar, which adds a very sweet flavor which makes kecap asin taste kind of like molasses. It also looks like molasses; it is extremely thick and dark. Other ingredients like star anise and garlic are sometimes added to kecap manis to enhance the flavor; in a situation where you need kecap manis and cannot find any, you can try giving molasses mixed with dark soy sauce a shot.

Indonesian cuisine has a number of fermented ingredients, much like cuisine from other regions of Asia. When handled well, fermented ingredients can keep for an extended period of time, making them ideal in warm, humid climates. Many cultures have also developed a taste for fermented foods ranging from kimchi to kecap asin, and it is possible to find unique regional dishes which showcase these ingredients. If you taste an Indonesian dish and have trouble identifying the flavor, it might be kecap; ask the cook, as cooks are often happy to share ingredients with curious diners.