Preheat your oven to 180°C (350°F). Prepare your ingredients by peeling and dicing the apples, chopping the sage, mincing the garlic, and zesting the lemon. Mix the apples, sage, garlic, lemon zest, breadcrumbs, nuts, olive oil, melted butter, rosemary, salt, and pepper in a bowl to form the stuffing.
Using a sharp paring knife, carefully create a slit along the length of the pork loin to open it like a book. Gently flatten the meat with your hands to an even thickness.
Spread the apple and sage stuffing evenly over the inside of the pork loin, leaving a small border at the edges.
Carefully roll up the roast, enclosing the stuffing inside, and tie it securely with kitchen twine at 1-inch intervals to keep the shape intact.
Pat the outside of the roast dry with paper towels to ensure even browning. Rub the exterior with a little salt, pepper, and a drizzle of olive oil.
Place the roast in a roasting pan and transfer to the oven. Roast for about 70 minutes, or until the internal temperature reaches 63°C (145°F) and the exterior is golden brown.
Once cooked, remove the roast from the oven and tent it with foil. Let it rest for 15 minutes to allow the juices to redistribute.
Slice the roast into thick, juicy rounds, revealing the flavorful stuffing inside, and serve hot for a festive presentation.
