Squeeze the mandarins to obtain 1lt (4 cups) of juice.
Filter it to remove pulp and seeds.
Pour the juice into a saucepan with brown sugar, cornstarch, lemon peel, and the cinnamon stick.
Heat the mixture, stirring constantly until it becomes thick.
Remove the mixture from the stove and take out the lemon peel and cinnamon stick.
Pour the mixture into the mold and then leave it to cool completely.
Before serving, garnish with strawberries, pistachio or you can sprinkle with powdered sugar.