Preheat your oven to 150 °C / 300 °F. Add egg whites to a bowl of a stand mixer (or a regular bowl if you are using a hand mixer). Whisk the egg whites until they form stiff peaks, then after a minute, whisk in the sugar, 1 tablespoon at a time, whisking constantly until the meringue looks glossy, for about 3 - 4 minutes. Add the lemon juice and corn starch and whisk for a second, just to combine.
Fill a pastry bag with meringue
Fill a pastry bag fitted with a 1 cm (0.5 inch) tip with meringue.
Place a baking paper over a large baking sheet. If you want you can draw 6 cm (2.5 inch) circles using a pencil on baking paper. Spread the meringue inside the circle, creating a crater by making the sides a little higher than the middle (leave space in the middle for the lemon curd). This recipe makes around 8 pavlovas. Place the baking sheet into a preheated oven. Lower the heat to 130 °C / 270 °F and bake for about 30 minutes, then lower the heat to 110 °C / 230 °F and bake for another 60 minutes. Turn off the heat and let the Pavlovas cool completely inside the oven.
Prepare the lemon curd. Add sugar and lemon zest to a saucepan. Add the lemon juice, stir well for the sugar to dissolve, then add 3 egg yolks and place over high heat. Cook for about 2 minutes, whisking constantly (it’s really important that the cream covers the back of a spoon (thick consistency), but be careful not to get scrambled eggs - whisk constantly.) Gradually add cubes of butter, one small cube at a time, until completely incorporated. Remove from the heat and blend using an immersion blender. Transfer the lemon curd to a bowl. Use your hands to lightly press the cling wrap, so that it is actually touching the top of the custard - that will prevent the skin from forming.TipDon’t put the lemon curd to the fridge, it will get too thick. Also if there are any lumps in the cream, press the mixture through a strainer.
Remove the pavlovas from the oven and fill them generously with lemon curd. Optionally you can sprinkle the lemon curd with chopped pistachios. Enjoy.