Lemon and Lime Cordial

Zest all the lemons and limes using a microplane zester. Set the zest aside.

Bring a large pot of water to a boil. Add the zested lemons and limes and blanch for 1 minute.

Remove the citrus from the pot. Reserve the blanching water in the pot.

Once cool enough to handle, cut the blanched lemons and limes in half and juice them into a separate bowl.

To the reserved blanching water, add the sugar and the reserved citrus zest.

Bring the mixture to a simmer, stirring to dissolve the sugar.

Pour in the fresh lemon and lime juice and bring the mixture back to a simmer.

Strain the hot cordial through a fine-mesh sieve into a heatproof container to remove the zest.

Let the cordial cool completely before storing in an airtight container in the refrigerator.

To serve, pour the cordial over ice and top with sparkling water.