1. Preheat oven to 225 degrees. Using a 1 1/2-by-2-inch oval-shaped cutter, trace 12 oval shapes on each of two sheets of parchment paper with a pencil. Transfer parchment paper, pencil side down, to two baking sheets; set aside.

2. In the bowl of an electric mixer fitted with the whisk attachment, beat egg whites and salt together until glossy peaks form. With mixer running, add sugar, one tablespoon at a time, beating until meringue is stiff and glossy. Sprinkle in cornstarch, vinegar, and vanilla; mix until meringue is just combined.

3. Transfer meringue to a pastry bag fitted with a 1/2-inch round pastry tip. Pipe a dollop of meringue in the center of each oval on parchment paper. Pipe meringue around dollop twice, creating a well to hold filling. Repeat process until all eggs are created.

4. Transfer to oven and bake until meringue lifts off parchment paper easily, 1 hour to 1 hour and 15 minutes. Transfer to a wire rack; let cool completely. Fill cooled meringue eggs with orange curd; serve.