Start by removing the rind from the watermelon. Cut the flesh into 18 evenly sized cubes and place them in a glass baking dish. Save any leftover watermelon pieces because they will be used to create the fruit syrup.
Place the watermelon scraps in a small saucepan. Add the chopped strawberries, sugar, and water, then bring everything to a gentle boil. Let the mixture simmer for several minutes until the fruit softens and releases its flavor.
Remove the saucepan from the heat and allow the mixture to cool completely. Cooling prevents the syrup from softening the fruit too quickly and helps preserve the fresh texture of the watermelon cubes.
Pour the cooled mixture through a fine sieve over the watermelon cubes. Make sure the fruit is evenly coated with the syrup. Allow the watermelon to marinate for about one hour so it absorbs the sweet berry flavor.
Thread one watermelon cube and one strawberry half onto each short skewer. Arrange the assembled skewers neatly on a serving platter. Their bright red colors make them instantly eye-catching.
Drizzle a little of the prepared fruit syrup over the skewers. Squeeze fresh lime juice on top and garnish with mint or lemon balm leaves if desired. Serve immediately for the freshest flavor.