What exactly is Korean chili paste, aka 'gochujang'? Is there any way of making it at home? I have recently started trying out some Korean dishes, some of which use the Korean  chili paste, gochujang. However, I can't seem to find this in any of my local supermarkets. 

What exactly is in this paste, which gives it that distinct flavour? Is there any way of making this at home, in a relatively easy way?
It is a fermented chili paste made with rice and fermented bean paste.

You could make it at home if you can find all the ingredients. But it looks like a complex recipe and preparation.

For example: https://www.youtube.com/watch?v=5IqtT0HcXUE

Here's a simpler version (less traditional) : https://www.youtube.com/watch?v=QiWJor3DQgI

I would substitute with any other chili paste (sambal oelek...)