I have grown soil sprouts following the book in your link.
I followed his program, using potting soil, home made compost and some liquid kelp in each pan. I used the small bread pans that he showed in the book.
I had some seeds on hand and bought a sprouting mix also. I started with 4 pans at a time, which actually was a little much for me, since i mixed it into romaine lettuce. I think he grows many pans at a time since he makes salads from the sprouts only.
I did cut the sprouts close to the soil line and washed them afterwards. I did try rinsing them before cutting also which was a little easier, but I don't remember which method worked best. After cutting the sprouts, I threw the remaining soil with roots in my compost pile, so no waste there. The next batch starts with fresh soil.
If you don't already have sprouting seeds, I found them at my local nursery in a sprouting seed section, separate from the regular seeds. Or online too.
It was a lot of fun. I grow warm season vegetables in raised beds in my yard, so was just trying this for fun. I have also grown lettuce and herbs inside using an Aerogarden. It's a tabletop hydroponic unit, lots of fun.