1. Preheat oven to 375 degrees. Position rack in center of the oven. Line a baking sheet with parchment paper.
2. In a large mixing bowl, use an electric mixer on low speed to beat egg whites and salt until frothy. Increase speed to high and beat until soft peaks begin to form. Gradually add sugar while beating, and continue beating on high speed until stiff, smooth, satiny peaks form. Add vinegar and potato starch and beat just until incorporated.
3. Scoop beaten whites onto parchment paper and spread with the back of a spoon to form a large circle, about 10 to 12 inches in diameter. Form a 2 inch-high border around the edge, smoothing the center to form a wide, shallow bowl. Place meringue in oven and immediately reduce temperature to 200 degrees. Bake for 1 hour, then turn off heat. Open oven door slightly and let cool in oven for at least 2 hours, up to overnight.
4. While meringue (shell) is baking, prepare the filling. In a medium saucepan, whisk together eggs, sugar, potato starch, salt, lemon juice, and orange juice. Cook over medium heat, whisking constantly, until mixture is very thick and bubbly, about 5 to 7 minutes. Watch carefully, as it goes fromthin to very thick in a few seconds. Remove from heat and stir in lemon and orange zests. Whisk until combined. Pour into a small bowl, cover, and refrigerate until chilled. May be prepared a day in advance.
5. When ready to serve, place pavlova shell on a large platter. If citrus filling has separated during chilling, stir to recombine. Spoon filling into center of shell and spread evenly into a large circle. Top with sliced strawberries and garnish with mint sprigs, if desired. Slice into wedges and serve immediately.
Source: Hannaford fresh Magazine, March - April 2012