- Pulverize dried mushrooms in a coffee grinder (make sure you clean out the grinder first!) until finely ground.
- Stir in thyme, mustard, cayenne pepper, and carrot powder.
- Season bison liberally with kosher salt and then rub with porcini rub. Let stand for about 1 hour.
- Preheat oven to 350 degrees. Place rib in a roasting pan on a wire rack. Roast until an internal temperature of 130 degrees, about 2 hours.
- Let rest for at least 25 minutes before slicing.