Add olive oil to a medium sized skillet over medium heat. Add leeks and saute for 8 minutes or until soft. Add garlic and saute additional two minutes.
Continue adding sage and rosemary and saute an additional 5 minutes. Remove from heat and add to the pork belly prior to rolling the Porchetta.
Coat the inside portion of Porchetta with 2 tablespoons of olive oil, dry rub, and filling. Roll the Pork Belly per the blog instructions and tie together with butcher twine.
Coat the exterior of the Porchetta with remaining olive oil and dry rub and filling. Place into the refrigerator covered for 24 hours to season.
Prepare the grill for two zone cooking and remove the Porchetta from the refrigerator.
Place Porchetta over the direct heat for 6 - 8 minutes or until you see a nice crust form. Rotate the Porchetta and cook over direct heat for additional 8 minutes or until you see a nice crust form.
Move the Porchetta to indirect heat, and add your meat thermometer probe into the center of the roast. Cook additional 2 hours and 30 minutes or until the internal temperature of the probe reaches 145 degrees F.
Remove the roast from the grill, and tent with foil. Let rest 30 minutes. Slice and serve with your favorite sides.