Preheat the oven to 155'C.
Whisk the egg whites with 150g caster sugar and the food colouring. Whisk until you have a stiff and glossy meringue mixture.
Place the icing sugar and the almond powder in a blender. Blitz and then sieve this mixture into a bowl to ensure that you have a very fine, lump-free powder.
Incorporate the dry ingredients into the meringue mixture. Use a spatula to cut and fold the mixture until it is smooth, shiny and ribbon-like.
Fill a piping bag with the macaroon mix and pipe the macaroons onto a lined baking tray. Leave the macaroons to dry slightly for 15 minutes at room temperature. Sprinkle the macaroon shells with the sesame seeds and then bake in the preheated oven for 10-15 minutes.
Zest the lemon. Sift the icing sugar into a bowl then add the softened butter, lemon zest and lemon curd. Beat together until you have a thick buttercream. Place in a piping bag.
Fill half of the macaroon shells with the lemon buttercream and then top with a second macaroon shell and gently sandwich together. Serve with a light dusting of icing sugar.
«Take care not to overwork the mixture as you fold the dry ingredients into the meringue - you want to avoid knocking all of the air out of the meringue.»