Mix together the rice, spring onions, lemon rind and dill. Cut the salmon into large chunks and stir through the rice.
Stir together the melted butter and oil. Unwrap 1 pastry sheet, leaving the remainder covered with a damp, but not wet, piece of kitchen paper. Brush all over with the butter mixture, then sprinkle a quarter of the rice mixture along one short side. Fold in the long sides of the pastry and roll up to enclose the filling completely.
Place on a baking sheet and brush with some more butter. Repeat with the remaining mixture and pastry. Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 15 minutes until golden and crispy. Serve with peas and sugarsnap peas.