I could have grilled this on a Weber grill but I did not (not enough time). I just browned the surface in a frying pan with olive oil (1 tbs), turning 90 degree every few minutes. I then finished in in a pre-heated 400F oven for 8-10 minutes or until the center of the rolls registered 150F. I let it rest for 5-10 minutes. When I served this for dinner, I may have made red wine sauce (I think).
I made this one evening and served it as the main course for dinner. The next day I served the leftovers as a drinking snack. I think this recipe is based on one in Cooks Illustrated.
Pork: I used my usual vacuum packed pork tenderloins. I trimmed and removed fat and sliver skin. I then cut it along the length of the tenderloin leaving 1/2 inch on the other side and opened it up like a book. Using a meat pounder, I flattened the tenderloin into a 1/2 inch thick rectangle.
Stuffing: You can use any kind of stuffing but the amount you can use is rather small so you should make it highly flavorful. For these two tenderloins, I used sun-dried tomato (packed in olive oil, 6-7 chopped), black (Karamata) olive (8-9 pitted and chopped), lemon zest (one lemon using micro-grater), garlic (2 cloves), fresh thyme (3-4 sprigs, stem removed), anchovy fillets (4 packed in oil). I put everything in a mini-food processor and pureed it until it became a stiff paste. I added a bit of olive oil and black pepper (It was plenty salty from the anchovy and olive).
Assembly: Since the stuffing was rather strong, I did not season the inside of the meat. I spread a single layer of baby spinach leaves (if you have them, fresh basil leaves would work) and then spread the stuffing. In the same manner as when I make sushi roll, I made a tight roll trussed it with butcher twine in two inch intervals (see image below). I smeared the surface with olive oil and seasoned it with salt and pepper.
A few days later, I just sliced it and drizzled on a small amount of olive oil. I probably overdid the anchovy but otherwise the stuffing was very flavorful and no sauce was really needed . I served this on a layer of cucumber slices which added a nice fresh contrast in flavor and texture.