Heat your oven to 275°F (140°C) for 15 minutes.

To make the pavlova, place the egg whites in the bowl of an electric mixer. Whip the egg whites until they are cloudlike, fluffy yet firm, about 3-4 minutes. Overwhipped egg whites will have a rough, jagged texture so watch the egg whites closely as they are whipping.

While the egg whites are whipping, in a separate small bowl, mix together the cornstarch and vinegar. Set aside.

Once the egg whites appear fluffy and firm, add the sugar one spoonful at a time, allowing to incorporate before adding the next spoonful, about 5 seconds. Once all of the sugar is incorporated, add the cornstarch mixture.  Whip for 5-10 seconds more, blending well. Turn off the mixer. 

Cut a square of parchment paper, and trace an 8″ circle (20-21 cm) onto the paper (I find this easiest to do by tracing around a clean mixing bowl) Spoon the pavlova mixture onto the parchment, following the pencil circle as your guide. Leave a hollow portion in the middle of the pavlova. 

Place the pavlova in the oven, and lower the temperature to 250°F (130°C). Bake for 1 hour, and then turn the oven off, allowing the oven to cool, and the pavlova to dehydrate for about 2-3 hours.

Meanwhile, to make the Hibiscus Syrup, place the water, hibiscus flowers and cinnamon sticks in a small saucepan, and bring to a boil. Simmer for 5 minutes over low heat. Remove from heat, and allow to cool. Strain the tea by filtering the liquid using a mesh strainer lined with a coffee filter, to remove all of the smaller leaf particles. Remove the cinnamon stick and discard.

Return the tea to the saucepan, and add the sugar. Bring to a boil again, and allow to gently simmer for 5 minutes, until the syrup is thick, and the sugar completely dissolved. Remove the saucepan from the heat, and allow to cool completely.

Meanwhile, to make the Hibiscus Syrup, place the water, hibiscus flowers and cinnamon sticks in a small saucepan, and bring to a boil. Simmer for 5 minutes over low heat. Remove from heat, and allow to cool. Strain the tea by filtering the liquid using a mesh strainer lined with a coffee filter, to remove all of the smaller leaf particles. Remove the cinnamon stick and discard.

Return the tea to the saucepan, and add the sugar. Bring to a boil again, and allow to gently simmer for 5 minutes, until the syrup is thick, and the sugar completely dissolved. Remove the saucepan from the heat, and allow to cool completely.

Once the pavlova shell and syrup are ready, assemble the pavlova right before serving.

Whip the heavy cream with sugar, until stiff, but soft peaks form. Rinse the berries, and pat dry well.

Place the cooled pavlova shell on a serving dish, and fill with the cream, spreading the cream evenly across the hollow middle. Arrange the berries on top of the cream.

Serve the pavlova immediately, garnishing with the Hibiscus syrup at the table, or allow each guest to add the syrup to their individual plate.