Mix the cream cheese with the lemon juice, chopped dill and plenty of black pepper. Spread over 4 large flour tortillas and cover with the smoked salmon. Roll up like a Swiss roll, trim off the ends and discard. Wrap tightly in cling film, twisting the ends firmly to enclose. Place in the fridge until you are ready to use. To serve, take a sharp knife and slice on the diagonal. Serve with extra dill and rocket leaves.