juice and finely grated zest of 1 lime, plus extra lime zest to decorate
100 ml (3 1/2 fl oz) water
1 small–medium watermelon
Place the grenadine, sugar and lime juice and zest with the measured water in a small saucepan and bring to the boil. Reduce the heat and cook gently for 6–8 minutes until thick and syrupy. Remove from the heat and allow to cool.
Meanwhile halve the watermelon and, using a sharp knife, slice the rind from the bottom of each half.
Lay the halves on a cutting board and, working from top to bottom, trim the rind from the watermelon flesh in 4 cuts, creating 2 large squares.
Cut each square of watermelon into equal bite-sized squares and place on a serving platter to form a neat large square (made up of the bite-sized squares).
Drizzle over the cooled grenadine syrup, scatter over the lime zest and serve immediately.