How to create procedural generated asteroids?

So as the title suggest i'm wanting to make a script that can procedural generate asteroids in game, i'm doing this as a way to learn the basics of PGC with the hopes of implementing it at a far later date as currently i haven't got a clue. My questions are:
1. Are the any guides for modeling and texturing from code in the unity engine that you guys recommend? (C#)
2. Anyone seen any PCG tutorials/articles that they thought where very good for the beginner, or where very in depth?

 

I'd suggest that, before doing PCG in three dimensions, do PCG in two. A good exercise would be to generate textures or terrain heightmaps using the code on this website: http://freespace.virgin.net/hugo.elias/models/m_perlin.htm