Preheat oven to 250 degrees. Use a pencil to trace a 10-inch-diameter circle on a piece of parchment. Trace a 6-inch-diameter circle in center of larger circle. Place on a baking sheet, tracing-side down.

In the bowl of an electric mixer fitted with the whisk attachment, beat egg whites on medium-high speed until soft peaks form. Gradually add 1 1/2 cups sugar, beating until stiff peaks form. Beat in cornstarch, vinegar, and vanilla.

Divide mixture between two large piping bags fitted with a 3/4-inch plain round tip. Pipe 10 evenly spaced mounds (each about 2 1/4 inches in diameter and 2 inches high) onto parchment in a circle using traced ring as a guide. With the back of a spoon, create a hollow in each mound. Bake until ring easily lifts off parchment, about 1 hour, 10 minutes. Turn off oven; let stand in oven 1 hour.

Gently roll some of the berries in a damp paper towel, then roll in remaining 3 tablespoons sugar to lightly coat.

To serve, whisk creme fraiche until thickened, then fold in lemon zest. Whisk cream to medium peaks, then fold into creme fraiche; divide among hollows in pavlovas. Garnish with sugared and unsugared berries.