Grease a 3cm-deep, 20cm x 30cm (base) lamington pan. Line base and sides with baking paper, allowing a 2cm overhang on all sides. Place sugar and 3/4 cup cold water in a heavy-based saucepan over low heat. Cook, stirring, for 5 minutes or until sugar has dissolved.
Meanwhile, place boiling water in a heatproof jug. Sprinkle over gelatine. Stir with a fork to dissolve gelatine. Add to sugar mixture. Cook, stirring, for 1 to 2 minutes or until combined. Set aside for 20 minutes to cool.
Using an electric mixer, beat gelatine mixture on medium speed for 5 minutes. Beat on high speed for 5 to 7 minutes or until mixture is thick. Add vanilla. Tint pink with food colouring. Beat until just combined. Spoon into prepared pan. Level top with a spatula. Set aside for 45 minutes to set.
Using a warm knife, cut into 3cm squares. Toss each square in coconut to coat. Serve.