Kaipen is a traditional Laotian dish made from freshwater green algae, primarily collected from the Mekong River and its tributaries in northern Laos, especially around Luang Prabang. The algae used in kaipen is commonly called “river weed.” The preparation process involves cleaning the algae thoroughly and mixing it with seasonings such as garlic, sesame seeds, salt, and sometimes tomato. The mixture is then spread thinly onto large woven mats or bamboo screens to dry under the sun.

Once dry, kaipen forms flat, green sheets. These sheets are usually fried until crispy before eating. They are often served with jaew bong, a chili paste made with buffalo skin, or other Lao dips. Kaipen is commonly consumed as a snack or appetizer.

The tradition of making kaipen is tied to the dry season when water levels in the Mekong drop and algae is abundant and accessible. Women in local villages typically harvest and prepare the algae. The process of making kaipen may take several days, involving repeated rinsing, seasoning, and sun-drying. This dish allows for preservation of a natural resource that is only seasonally available.

Historically, kaipen has been made and consumed by Lao people for generations, especially in the mountainous north where other snack foods may be scarce. While originally a local food, kaipen has gained popularity among tourists due to its unique flavor and crispy texture, leading to its presence in markets and restaurants that cater to visitors.

Due to its nutritional content, kaipen is valued locally. It contains minerals, protein, and vitamins derived from algae. Some commercial production exists, with packaged kaipen exported to other countries, promoting Lao cuisine internationally. The dish reflects local resourcefulness and adaptation to the natural environment.