Place Leggo's Pesto, breadcrumbs, nuts and spring onions in a large bowl and stir until combined to make a stuffing mixture.
Lay pork loin flat, rind side down. Spoon stuffing in a log shape along the length of the loin. Roll up firmly and tie with cooking string at regular intervals to secure. Score rind. Rub rind with oil and rub in salt, turning over to coat well. Place in a lightly greased baking dish, seam side down.
Bake in a preheated oven at 220°C for 15 minutes. Reduce heat to 190°C and cook for a further hour. Rest for 20 minutes. Serve with roasted vegetables.