From "Fired Up! More Adventures & Recipes From Hudson's On The Bend" (another cookbook everyone should own).  Pretty simple but way impressive.  No pictures here but the peppered cranberry relish was the perfect topping.  Found a great place for the buffalo, Eichten's Hidden Acres in Center City.  Ed actually delivered it to me (along with 4 buffalo ribeyes which I can't wait to try). 

Started the day before by halving a turkey tenderloin and blackening it in a cast iron pan. Once it's done, let it cool and put it in the fridge until the next day.

Make a hole down the center of the bison tenderloin using a boning knife and shove the turkey inside.  A little cooking oil rubbed in the hole helps.  Add a little salt and pepper to the bison and you're ready to grill.

Toss it over a hot fire for about 5-6 minutes per side.

Let it rest for five minutes and slice it into half inch slices.  Expensive but impressive and well worth it (especially when you add the relish).