Heat 1 tablespoon olive oil in a heavy bottomed saucepan over medium high heat. Add shallots and cook until fragrant, about 2 minutes. Stir in garlic and cook for 30 seconds, then add mushrooms. Season with salt and pepper and cook, stirring occasionally, for about 8 minutes.
Transfer vegetables to a bowl and mix in sun dried tomatoes, olives, breadcrumbs, and parsley. Stir well and set aside.
Lay your pork loin flat on a large cutting board. Using a sharp knife, carefully butterfly the loin---cut along the length of the meat without cutting all the way through so you can open it up like a book. Cover with plastic wrap and use a meat mallet or rolling pin to pound pork until it's about ½ an inch thick. Discard plastic wrap.
Season butterflied pork with salt and pepper, then scoop vegetable mixture into the center of the loin, staying about ½-1 inch away from the sides. Gently roll your roulade shut, leaving the seam side down. Using kitchen twine, truss the roulade every 2 inches or so, tucking the strings in on the ends.
Heat remaining olive oil in saucepan over medium high heat. Add roulade, cut side down, and sear for about 4-5 minutes per side. Transfer roulade to baking sheet and bake for 20-25 minutes, until pork is cooked through. Let rest for 10 minutes before removing twine and cutting into 2 inch pieces.