thread·bare ( P ) Pronunciation Key (thrdbâr) adj. Having the nap worn down so that the filling or warp threads show through; frayed or shabby: threadbare rugs. Wearing old, shabby clothing. Overused to the point of being worn out; hackneyed: threadbare excuses
I was confused by that too, it says the main ingredient is raw roots or threadbare. If you examine the recipe straight from your list of recipes it says raw roots or raw threadbare. I think it's a mistake, raw threadbare doesn't exist.
Bobbin Threadbare: Main Character from Loom; One of the best Lucasarts games to date. Realeased in early 90's on 3.5 floppies and then rereleased on CD-Rom with a full score and voice over work.