Heat oven to 250°F (120°C). Line a cookie sheet with parchment and draw an 8–9 inch (20–23 cm) circle; flip parchment over.
Beat egg whites with a pinch of salt until foamy, then to soft peaks.
With mixer running, add sugar gradually and beat until thick, glossy, and stiff peaks form.
Mix in cornstarch, white wine vinegar, and vanilla extract just until combined.
Spoon onto the circle, shape into a round, and make a shallow nest in the center.
Bake 75–90 minutes until the outside is dry and set. Turn oven off, crack the door, and cool in the oven at least 1 hour.
Whip heavy cream with powdered sugar and vanilla to soft-medium peaks.
Top pavlova with whipped cream and strawberries. Slice and serve.