Preheat oven to 325 degrees F.
Beat egg whites and vinegar in a stand mixer or place in a large mixing bowl and use an electric mixer until stiff peaks form. Set aside.
In a large bowl, whisk together remaining ingredients.
Fold egg whites into egg yolks mixture.
Grease pie dish and pour filling in.
Place a pie plate into a large roasting pan for a water bath.
Place roasting pan in oven and pour in hot water half way up sides of the pie dish.
Bake 50-60 minutes until lightly golden brown and center is set and allow to cool then refrigerate until chilled. Add some fresh berries and sugar free whipped cream to serve this scrumptious pie.
Storage; Once cool you can cover the entire pie and refrigerate for up to 7 days or you can place individual pieces in an airtight container and store in the fridge or freeze for up to 3 months.