Add the egg whites, corn starch into a bowl and beat at medium speed until the egg whites become white and silky. Gradually add the sugar then the vinegar and finally the vanilla. Your meringue should now form stiff peaks.
Pre-heat your oven to 200F and line a large baking sheet with parchment paper. Empty your meringue into a piping bag with a ½ inch tip and pipe nests onto the parchment (leave 1 inch of space between each nest).
Bake on the middle rack for 70 minutes or until outside is firm. Allow to cool for 2 hours or overnight.
Carefully remove from parchment. Store in a tupperware stype container in a cool-dry place.
For the lemon curd, use a vegetable peeler to remove the peel (no white pith) and place in a food processor with the sugar. Pulse until the lemon peel becomes fine and blended well with the sugar. Now add the butter and process until blended.
Add the eggs one at a time and finally the lemon juice.
Transfer to a medium pot, add a pinch of salt. Cook on medium-low while stirring for about 10 minutes (or until curd reaches 170F. Remove from the heat and allow to cool. Cover with plastic wrap if storing in a fridge.
Before serving, add the fruit in the bowl and gently mix.
To serve, place meringue nest on a plate, a layer of lemon curd top with the berries and mint. Dust with some icing sugar.