Preheat oven to 160C / 320F.
Use a large clean mixing bowl, without any trace of oil or water, beat the egg whites with an electric mixer until bubbles form. Add lemon juice. Gradually add the sugar, one-third at a time, and beat well between additions. Continue to beat until stiff peaks form.
With a spatula, lightly stir in lemon zest. Sift in and lightly fold in the cornflour in three batches. Add the desiccated coconut.
Use an ice-cream scoop or large spoon to drop heaped tablespoons of mixture onto a lined baking tray, leaving about 3cm / 1¼ inch between each as picture shown. Bake in the preheated oven for 20 minutes, or until pale golden. Remove the tray from the oven and leave for 5 minutes before transferring the macaroons onto a wire rack to cool completely. The leftovers can be stored in an air-tight container for a few days