Preheat oven to 250F and line a baking sheet with parchment paper.
Beat egg whites and pinch of salt on medium until frothy. Gradually add in sugar and continue beating on high until sugar dissolved.
Mix corn starch and powdered sugar together. Add to egg whites and continue beating for 5-7 min until batter is glossy and very stiff.
Put chocolate into the pipping bag and melt in the microwave using 15-20 sec intervals.
Add lemon juice into meringue and continue beating for another minute.
Drizzle melted chocolate over meringue and mix with help of the spatula for 2-3 time (not more).
Spoon out mixture and drop onto parchment paper.
Lower oven temperature to 200F and bake meringue for 2 hours. Do not open oven door! Let the meringues cool completely in the oven.
Gently peel chocolate meringues from the parchment paper and serve with fresh raspberries or other berries.