Grind all dry ingredients in an electric spice mill; then blend in small bowl with olive oil and set aside. Next, pierce tuna loin completely through with a small wooden skewer to create starter holes for the dowels. Then very carefully slide oiled dowels through the tuna. Carefully rub spice mix on tuna and refrigerate until ready to toast. When the mood is right and the fire is roasting, toast the tuna over an open fire until medium rare (about 15 seconds per side.)