Place the caster sugar into an oven dish and place into a hot oven (220C/200C) for roughly 5 minutes until the sugar is hot but not yet melted.
Take the sugar out of the oven and immediately begin whisking the egg whites in a large bowl.
Once the egg whites have formed stiff peaks, turn the whisk speed to maximum and begin adding the warm sugar one spoon at a time.
Make sure that the egg whites are forming stiff peaks again before adding in the next spoon full.
Once all of the sugar has been added to the mixture, whisk on high for another 5 minutes to ensure the egg whites are thick, firm and glossy.
Next, take the two icing bags and paint red and green stripes in each with the food colouring.
Fill the piping bags with the meringue and cut a large opening at the bottom of each bag.
Pipe a small amount of meringue on to a large baking tray and then line the tray with grease proof paper (the little bit of meringue in each corner will help it stick).
Begin piping the meringue kisses in the top left hand corner.
Hold the piping bag upright, squeeze gently and lift away as you stop applying pressure.
Repeat over and over again until the whole baking sheet is covered and all the meringue used up.
Cook the meringues in the centre of the oven for 30-45 minutes at 100C/80C or until the meringue kisses come off of the baking paper without leaving their bottoms behind.
Allow to cool completely before serving.
Notes
These will keep in an air tight container for up to 2 weeks (if you can resist them!)