1. Make the filling Melt the oil and butter together and fry the bread until crispy. Move to the side of the pan and now fry the apple, garlic and dates for a few minutes until the apple starts to soften. Mix the bread with the apple mixture and stir in the pecans and rosemary. Remove the filling from the heat, season to taste with salt and pepper and allow to cool.
2. Place the deboned rib with the fat side down on a clean surface and spread the filling across the middle of the meat. Fold the meat tightly over the filling until the edges just come together and tie in a neat roll with kitchen string – aim for a single outer layer of meat with filling in the middle, rather than a spiral of meat and filling.
3. Preheat the oven. Arrange the lamb roll and potatoes in a deep ovenproof dish and sprinkle with the oil. Bake for about 1 hour or until the meat and potatoes are golden-brown and cooked through. Remember to let the meat rest before you carve.