Mencia grape

Hey all, rising popularity in recent times for Mencia wine. Especially from Bierzo DO and Ribera Sacra DO.

For the blind tasting, What do you think is the main clues that indicate the wine is Mencia? 

Second, I have a friend that never heard of this. He knows his wines and regions and producers. I want to gift him with a crazy producer incredible wine from Ribera Sacra specifically, what would you recommend?