Start by preparing the simple syrup: in a pan add the water and sugar and stir until combined.
1 cup water, 1 cup white sugar
Add the orange halves, side down, and turn the heat on to medium.
2 medium oranges
Bring it to a bare simmer, then add the rosemary and let it all infuse for 5 minutes.
4-6 sprigs fresh rosemary
Slightly crush the citrus with a spoon, then cover with a lid and let it simmer for a further 15 to 20 minutes, stirring and crushing the citrus every so often.
Turn off the heat, strain the mixture and pour into a clean jar for storing, at this point, you can add a drop or two of food colouring to get the right hue but it's optional.
yellow & red food colouring
When you are ready to enjoy the mocktail, add ice to a glass and add the syrup, then top it with soda water.
120 ml orange rind simple syrup, 240 ml sparkling water, ice, 2 orange slices
Gently stir so that the syrup and soda water combine.
Garnish and serve immediately.