When ravaging a battle-hewn corpse for parts, it's not always easy to keep the bowels intact. Most ghouls don't mind a few stitches here or there to keep the sausages in nice shape. It's worth the extra reinforcement, too, because it's not a simple task to grind up Ironbreakers so that they've got a nice, smooth consistency.
Talk to Nathore Gristlechewer at 56700,39400 in Ostland while having a Portion of Dwarf Meat in your inventory. Portion of Dwarf Meat drops from Hammerstriker Port Guards and Hammerstriker Veterans in a tower in Thunder Ridge Tower in Barak Varr (south west of the Order Warcamp around 17000,49000). The Portion of Dwarf Meat will disappear when you receive the unlock.
This tome unlock contributes to the Ghoulish Gourmet pursuit.