Method

Preheat oven to 150c/130c (fan), place the egg whites into a mixing bowl and use an electric mixer to whisk on high speed until a stiff peaks form. Gradually add the sugar, 1 tablespoon at a time, waiting 30 seconds before adding more. Once all the sugar has been added, whisk for a further 6 minutes or until the mixture is stiff and glossy. Scrape down the side of the bowl, add the vinegar and whisk for a further 2 minutes, or until glossy and combined.
Draw 8 x 10cm circles on 2 large pieces of non-stick baking paper to fit 2 large baking trays, allowing room for the mixture to spread. Divide the meringue between the circles and top each with 1 teaspoon of dulce de leche or caramel sauce.
Using a palette knife, swirl the mixture and spread to the edge of each circle. Sprinkle with the salt, reduce the heat to 120c/100c (fan) and bake for 30 minutes, or until crisp to the touch.
Turn the oven off and allow the meringues to cool in the oven for 30 minutes.