I would recommend either the Vega Telanga Tercio or the Hoyo Dark Sumatra. Both have a very earthy and almost pungent taste.
I disagree with the Nicaraguan recommendation, I have found Nicaraguan tobaccy to have a rather dark/semi-sweet flavor. But depending on the blending almost any cigar can have a earthy taste.
Not to threadjack, but i had a L.F. Dominicana Ligero the other day, and WOOHOO, a damn fine smoke it was!