Preheat oven to 450 degrees. Salt and pepper roast.
Pesto:
Add cranberries, garlic, basil and cheese to the food processor. Roughly chop.
Add orange pieces and oil. Process into chunky pesto.
Spread 1/2 cup of pesto over roast. Cook at 450 for 15 minutes.
Reduce oven to 325 and cook roast for 41 minutes. Test for doneness (approximately 130 degrees) with an internal thermometer.
Remove roast. Cover with foil tent and rest for 15 minutes before slicing. Serve with remaining pesto as relish.