Mixed Berry Pavlovas

Ingredients

• 1 lb blackberries 
• 1.5 tablespoons cornstarch 
• 13 large egg whites 
• 0.3 cup granulated sugar 
• 2.5 cups granulated sugar 
• 2.5 cups cup heavy whipping cream chilled
• 3 tablespoons juice of lime fresh
• 0.3 teaspoon salt 
• 2 teaspoons vanilla 
• 1.5 tablespoons vinegar white
• 2 lb strawberries halved quartered

Equipment

• bowl
• baking sheet
• sauce pan
• oven
• hand mixer

Directions

1. Preheat oven to 250°F and line 2 large baking sheets with parchment.
2. Swirl whites in a metal bowl set over a saucepan of simmering water until barely warm to the touch. Beat whites with salt in a standing electric mixer until they hold soft peaks. Beat in 2 cups superfine sugar and continue beating until mixture holds stiff, glossy peaks (see cooks' note, below). Stir together remaining 1/2 cup superfine sugar and cornstarch. Beat into meringue, then beat in vinegar.
3. Spoon 8 mounds of meringue (each about 2 inches high and approximately 1/2 cup) 1 inch apart on each lined baking sheet. Divide any remaining meringue among mounds.
4. Bake in upper and lower thirds of oven, switching position of sheets halfway through baking, until crisp but still soft inside, 1 to 1 1/4 hours total. If meringues are still not crisp after 1 1/4 hours, turn off oven and cool in oven 1 hour.
5. Transfer from parchment to racks to cool. (Meringues may stick if cooled completely on paper.)
6. Just before serving, toss strawberries with lime juice and 1/4 cup granulated sugar and let stand, tossing occasionally until sugar is dissolved, 10 minutes.
7. Add blackberries and toss to coat.
8. Beat cream with vanilla and remaining 1 1/2 tablespoons granulated sugar with cleaned beaters. Tap meringues gently with back of a spoon to create indentations, then mound some whipped cream and berries onto each.