I think it's true to say that cultures who eat rice as a staple must have some kind of congee too, which is essentially overcooked rice turned into a soupy gloop. That might not sound very appetising, but for many Asians it is the dish that we turn to when we are ill and all you want to eat is something light and comforting. The method of preparing congee varies greatly in different parts of Asia. I recently learnt from a Japanese friend that in Japan they actually use cooked rice to make congee - which would presumably shorten the cooking process considerably. There are many different forms of congee in India too, and they no doubt display an ingenious use of different grains and spices. In China the staple congee is the plain congee made from white rice, although there is an infinite number of variations using whole-grain rice and other grains, even with medicinal herbs. The consistency of congee in China also varies a great deal. I remember the kind of congee that I was brought up eating (Hokianese) is kind of more like overcooked rice than a rice porridge - similar to Teochew congee 潮州粥.
The most sophisticated way of preparing congee in China has got to be Cantonese congee 明火白粥. You start off (ideally) by combining new season rice and old rice - one gives flavour and the other stickiness. The rice is first marinated in salt and oil which makes it easier for the rice grains to exude their inner starchiness during the cooking process. The rice is then added to a copious amount of boiling water (the rice to water ratio is about 1:18), and cooked for one and a half hours (or even longer) uncovered with a few slices of ginger until it becomes a homogeneous rice-soup, with the grains still visible and the water loosely bound together by the starch. It's a lengthy process, and one has to stir the bottom of the pan from time to time to prevent scorching. Dried scallops, tofu skin and tangerine peel are often added to give the congee a greater depth of flavour. After preparing plain congee, you can use it as a base for other flavoured congees like 皮蛋瘦肉粥, 柴魚花生粥, etc.
I used to hate congee ever since childhood. Now, maybe because of ageing, I've warmed to its plainess, its simplicity that celebrates food at its most elemental and pure.
2 cups of rice yielded this much congee!!