Beat egg whites until soft peaks form.

With the mixer running, add sugar one tablespoon at a time, until stiff peaks form.

Preheat oven to 250 degrees Fahrenheit. Line a sheet pan with parchment paper or a silicone baking mat and set aside.

Add meringue to a clean piping bag fitted with a large-star decorating tip (approximately 1/2-inch opening).

Pipe a three-inch circle onto the prepared sheet pan. Fill in completely with meringue. Pipe another layer around the outer edge, leaving the center empty.

Continue forming the pavlovas until all meringue is used.

Bake two hours or until pavlovas are completely dry but not browned.

While the pavlovas bake, whisk together egg yolks, sugar, and lemon juice in a medium saucepan.

Whisk in potato starch until completely dissolved.

Turn on the stove to medium heat and simmer 15 minutes or until mixture thickens, whisking constantly.

Remove from heat and stir in margarine or frozen oil, a little at a time, until fully incorporated.

Transfer curd to a bowl and cover with plastic wrap, pressing plastic directly onto the curd to prevent a skin from forming.

Place a pavlova on each dessert plate and spoon lemon curd into the center. Serve immediately.