A slurry is the yeast that is left in the bottom of the primary bucket when you rack your wine to a secondary.
as far as a recipe, it's hard to beat the original. http://skeeterpee.com/?page_id=17
And it is highly recommended that you collect your slurry before it has dropped below SG of 1.010. Recommend having a package of EC-1118 on hand just in case, but usually you are fine with your slurry.