Māori never cooked in the same buildings that they slept in. Instead kai (food) was prepared in the open air or in special cooking sheds.
The hāngī or earth oven is a traditional Māori method of cooking, especially suited to preparing food for large numbers of people. Hot rocks and water are used to create steam in a shallow pit dug into the earth. The food is layered on top of the rock (meat first, then vegetables) and covered with leaves, whāriki (flax matting) or, in more recent times, sacking or cloth. The soil is then replaced to trap the steam for a few hours. The exact time depends on the size of the hāngī.
In regions such as Rotorua hāngī have for centuries been cooked using geothermal steam.
Smaller quantities of food such as fish and birds were grilled on sticks over glowing embers. Birds might also be wrapped in clay, or fish in leaves, and placed on the embers.
Since Māori did not make pottery, their only means of boiling food was to place a red-hot stone in a wooden bowl of liquid.
Understanding the effect of the moon on preservation and preparation of kai was very important. In 2012 Charles Royal, a chef specialising in traditional Māori foods, remembered his grandmother Cinny Callaghan drying tuna (eel): Royal said that she would bring the kai inside at night, out of the light of the full moon, so it would not sour or spoil.
Māori preserved large quantities of food, to save for leaner times or to trade with other tribes.
Food could be dried in embers or, in the geothermal Rotorua area, spread on hot rocks. Foods commonly dried included kūmara, shellfish (such as pipi) and fish (such as shark and eels). Shellfish were threaded onto long lengths of twisted flax and hung from lines or whata (platforms) to dry in the sun and wind. Meat, fruits and seeds were also dried.
Fatty birds such as tītī (muttonbirds) were preserved in their own fat. After cooking, the hot fat was set aside. The meat was packed into hue (gourds), and the fat poured in to set around it. Southern tribes inflated pōhā (bull kelp) to make storage containers for tītī.
Mara kai is a traditional fermentation process for food such as crayfish and fish. After European arrival, it was also used for kānga (corn). The kai is placed in a kete (flax basket) and steeped in very slow-running water for days or weeks until the kōpiro (inner flesh) settles to the bottom of the kete. Although the smell becomes pungent, the kai is safe to eat and a delicacy to those who have acquired the taste for it.
The varieties of kūmara eaten today are quite different from the varieties eaten before-Europeans arrived. The most common modern kūmara, Ōwairaka Red, was introduced by a whaling ship, the Rainbow, moored at Ōpōtiki in the 1850s. A carpenter on board noticed the large Rarotongan sweet potatoes on board, and took some away to propagate. Māori soon replaced their traditional varieties with the new waina (vines), so-called because cuttings could be taken from their long, trailing shoots.
Whata were elevated platforms to hold or hang kai from until it could be stored more permanently in pātaka (storehouses) or rua kūmara (underground storage pits). Whata had thatched tops and protected the crops from kiore (rats) and the elements.
Rua kūmara were sited on slopes or other free-draining places so water never sat inside them. Whole kūmara were carefully placed on shelves cut into the inner walls of the pit. The kūmara were regularly checked for rot and rotated to ensure they stayed dry. If the kūmara did start to rot, they could be preserved by fermentation, producing kōtero. Kōtero looks shrivelled but maintains a rich, sweet flavour.