Kaukau came to PNG around 400 years ago, all the way from South America - probably brought by sailors who travelled across the Pacific. Highland farmers tried it, found it grew brilliantly in their cool, high gardens, and very quickly it became their favourite crop. Today they grow more kaukau than almost anything else.
Highland gardens are amazing places. Long mounds of soil sit in neat rows on the steep slopes. Each mound holds several kaukau vines. The leaves of the vine are eaten too - boiled like spinach. So one plant gives you two foods: a starchy potato underground and a leafy green above.
Kaukau is also the main food for the pigs. Pigs are very important in the Highlands - they are part of family life and special celebrations. The leftover kaukau (the smaller ones, the chipped ones) gets boiled up for the pigs. Healthy pigs and healthy people both depend on a good kaukau harvest.
If you visit a Highland family, the first thing they will offer you is probably a hot kaukau. You break it open with your hands, blow on it, and eat the soft sweet inside. It tastes a little nutty, a little caramel-y. Some kinds are so purple inside they almost look like fudge.