Grind grain of course! You even take your trusty sourdough starter named Arnold, and give him 100% whole wheat flour to eat. Then you take the starter you pull off, add some water, whole wheat flour, rye flour, and salt. You mix it together, let it sit overnight or longer, shape it, and let it sit till it's risen to just the right level, and then pop it into the oven! Nummy, bread, not as holey as I am used to, but very good tasting and I am sure it will get better with time. Overall though a nice tasting and looking loaf.