Heat 3 tablespoons olive oil in a frying pan over a medium heat. Stir in pine nuts, and cook until golden brown. Remove with a slotted spoon, and drain on kitchen roll. Place shallots in the frying pan. Cook and stir until tender, about 5 minutes. Mix in garlic and sun-dried tomatoes, and cook 2 minutes. Remove frying pan from heat, mix in pine nuts, breadcrumbs, and parsley. Season with salt and pepper, and set aside to cool.
Slice the sirloin lengthways across the top about 2/3 of the way through the meat to create a pocket. Spread stuffing into the pocket. Wrap the sirloin with kitchen twine to secure the stuffing, and transfer to a roasting tin. Rub the remaining olive oil over the surface of the meat. Season with salt and pepper.
Roast in the preheated oven for 15 minutes. Lower oven temperature to 180 C / Gas 4 and continue cooking for 20 minutes, or to a minimum internal temperature of 65 degrees C. Remove from the oven and let the meat rest for 15 minutes before serving.