Mix the flour with the baking powder. Add the margarine, sugar, eggs, lemon juice, and lemon zest. Stir to combine. Add the chocolate and strawberries. Bake in the centre of the oven at 200°C for about 20 minutes. Allow to cool. Whip the cream with the icing sugar until it forms soft peaks. Rinse the strawberries. Pipe or spoon a little whipped cream on top of each muffin. Decorate with strawberries.