Here is a link
to the Dirt Doctor potting soil recipe. Here it is in a nutshell:
40% coconut fiber
10% expanded shale
10% mix of lava sand, greensand, and alfalfa meal
I don't usually have everything on the list handy, I can't find some of this at local vendors, so I have a "vibration" method of making potting soil - the old "add to it and move it around till it looks good." I have compost in the yard, and will pick up top soil and humate at Home Depot and add decomposed granite and the green & lava sand amendments, mixed with my compost. I tend to use this to plant things that are going to go outside later anyway.
I know that the bagged commercial soil and such are the weak link in this organic chain, but by the time my compost has had time to work on it, I think it improves what I consider a fairly neutral or sterile material. And of course when I plant or transplant, I use the Garrett juice and good watering/fertilizing methods.