I know there’s a mod that gives Black Hand tents as a recipe you can find, but not an official recipe in the game.
Look for Exiled Lands Improved: https://steamcommunity.com/sharedfiles/filedetails/?id=1456186728
You can also read about the mod here in the forums: https://forums.funcom.com/t/mod-exiled-land-improved/29272. @Alex02 has done a fantastic job with this mod, with frequent updates, and keeping everyone informed of the progress and changes. You should really check it out!