Pre heat oven 120 degrees celsius or 100 degrees celsius for fan forced.
Separate 4 eggs and place egg whites into a large mixing bowl. (note: ensure bowl is dry and free of any residue. Water, oil or other residue will stop the eggs from aerating successfully)
Using whisk, beat egg whites until stiff peaks form.
Add 1 teaspoon white vinegar and beat again quickly.
pour a small amount (up to a quarter of a cup) of castor sugar into mix and beat until incorporated. Keep adding sugar and beating until all sugar is used and the mixture looks glossy, with firm peaks.
Grate chocalate (approx 6 small squares) and add to mix.
Fold in the chocolate with a spatula until just mixed.
Line a baking tray with greaseproof paper.
Take a teaspoon and scoop a small portion of the mix. Using a second teaspoon create a quinelle (or small round ball) of the mixture on the baking sheet. Continue until all mixture is used.
Place in pre-heated oven for 25 minutes or until meringues sound hollow when gently tapped.
Turn off oven and leave meringues in the oven until cooled.
Gently tear meringues from baking paper and store in an air tight container.