Heat oven to maintain about 500 degrees F.
In a food processor or by hand, finely chop herbs and stir in olive oil. (Note: Fresh herbs are preferable, but you can use dry herbs as well. If you use dry herbs, you’ll need less of them, as they are generally have stronger flavors - about 1/3 the amount of fresh.)
Using a sharp knife, roll cut the pork shoulder and tenderloin to approximately ½ inch thickness. Laying each piece flat, evenly spread the herbs and massage into the meat.
Place the seasoned tenderloin herb side up onto the shoulder and role the shoulder over the tenderloin. Wrap with bacon and tie with cooking twine several times holding each piece of bacon and tightly wrap. (You can let the roast rest in the refrigerator up to 24 hours at this point to allow the herbs to marinate into the meat, or cook it right away.)
Heat a 12” cast iron skillet in the oven to about 350 degrees F.
Lightly oil the pan and place the Porchetta in the pan. Cook at the furthest wall from the fire and partially close the door to the oven to maintain about 500 degrees F. Turn every 15 minutes and cook for a total of approximately 1.5 hours or until internal temperature reaches 145 degrees F.
Let rest for 15 - 20 minutes. Slice into ¼” steaks and serve by itself as a main dish with veggies, or in a sliced Ciabatta roll.