When the first Polynesians arrived on the Islands that would become known as Hawai`i, they did not bring any Wolf ovens with them. But they did bring along the knowledge of a cooking technique that was popular throughout Polynesia, Melanesia, Micronesia, and even in the Americas. This method of cooking was called kalua (ka, meaning the; lua, hole), which refers to a process of cooking in an earthen oven, called an imu. Kalua literally means, “to cook in an underground over,” but also describes the type of food cooked, such as the kalua pig, which is the most commonly served item at a traditional Hawaiian lu’au (feast).

An imu was a pit approximately two to four feet deep—depending on the size of the pig and meal that was being cooked—with sloping sides. The pit was made large enough to not only hold the food to be prepared but also the rocks and vegetation that made up the components of the imu. Essentially an underground pressure cooker that could take hours to create, the imu was used by Hawaiians to steam pig, breadfruit, bananas, sweet potatoes, taro, chicken, and fish for group meals, festivals, or religious ceremonies.

Once the hole was dug, kindling material -- such as twigs, leaves, and small branches -- were placed in the bottom. Larger wood was placed on top of this kindling and finally stones, roughly the size of a grown man’s fist, were positioned on top of the wood. The ideal stone used for an imu was vesicular basalt stones, due to their porous nature and ability to retain heat without exploding.

Once the stones were hot and the imu had reached maximum heat—a process, which usually took up to three hours—the stones were leveled out with a large stick and the imu was ready for final preparation. Imu cooking requires steam, so green plant materials such as banana stumps, ti leaves, honohono grass, banana leaves, and coconut palm leaf were laid over the hot stones. The term for this is hali’i (to spread like the mat covering the floor).

This first layer of hali`i prevented the food from being scorched by the rocks and created the steam for cooking. A second layer was then added. This layer was traditionally made of ti leaves because it would touch the food and thus would add flavor while the meal was cooking. The imu was now ready for the food to placed into it. If a large pig was being cooked, hot stones would be placed inside the body cavity to ensure that the meat was well cooked.

Finally, a third hali`i made of ti leaves and young banana leaves as well a old lauhala mats or worn tapa cloth covered the cover entire imu, extending beyond the diameter of the pit to keep the final layer of dirt from falling into the food. The dirt layer sealed the imu and kept the heat and steam inside.

Cooking times varied based on the size and type of the meal and the size of the hali`i, but on average cooking times were from six to eight hours. Once the cooking was complete the dirt was carefully remove and the food served—ready for a mouth watery meal with family and friends.

While this method of cooking took much longer than today’s microwave or convection ovens, the end result was often much more appealing and appetizing and it brought together the community of Hawaiians for grand feasts.