Place the flour and salt in a bowl and make a well in the middle. Break in the egg and gradually whisk in the milk to produce a smooth pancake batter. Before frying the pancakes, whisk in the melted butter. To cook the pancakes, heat up a large, non-stick pan and add in a little oil or butter. Pour a ladle of the pancake mixture into the pan and swirl around to coat the base of the pan. Cook the pancake for a minute or so, and then turn around onto the opposite side and continue to cook for a minute. Turn the pancake out onto a plate and repeat the same process with the remaining batter. Meanwhile, mix together the ricotta, icing sugar, lemon zest and vanilla. To fill the pancakes, place a tablespoon of the ricotta filling into each pancake with a few pieces of sliced strawberries, fold in half, then into quarters. Place 2 filled pancakes onto each serving plate and decorate with icing sugar, grated white chocolate and extra strawberries.