Draw circles with the approximate diameters of 4cm, 5cm, 6.5cm, 8.5cm, 10cm, 12cm, and15cm on parchment paper.
Whisk egg whites on high speed for approximately 1-2 minutes.
While whisking, add sugar 1 tablespoon at a time.
Whisk until thick, glossy and no sugar grains remain.
Stop whisking, sift cornstarch over the surface and add vinegar before continuing whisking until meringue is stiff.
Transfer meringue into a star-tipped piping bag.
Pipe tight coils onto pre-drawn parchment paper using the drawn circles as a guide, leaving approximately 1.2cm space from the edges.
Pipe another layer on top so that it's approximately 2cm thick and smooth surface with a palette knife.
Pipe decorative edge with an up and down motion.
Reduce the oven temperature to 120°C to bake the meringue for an hour.
Once done baking, leave the pavlova in the oven to cool for at least 3 hours, or even overnight. Make sure the bottom is dry and crisp.
For strawberry coulis, heat strawberries and sugar over medium heat. Simmer 5 minutes, mash the strawberries with a fork. Puree with a blender. Cool for at least 2 hours before use.
For whipped cream, whisk cream, vanilla and sugar on high speed until stiff. Set aside in the refrigerator until you start building.
To construct, place the largest Pavlova round on a serving platter. Spread with a layer of whipped cream, right to the edge. Place strawberry rounds around the edge. This is to provide support for the next layer. Scatter some diced strawberries in the middle. Drizzle with strawberry coulis. Spread cream over all of the strawberries. Make sure the cream is level. Stick a skewer in the middle for more support. Repeat this for each layer until you reach the top pavlova.
Decorate with sprigs of rosemary and halved strawberries. Strawberries could also be used to do any last-minute leveling.