Add tartaric acid to juice and stir to combine.

Add sugar and water to a saucepan, along with the zest, and stir over medium-high heat until the sugar dissolves and the mixture just starts to simmer. This should take about 5 minutes. Remove mixture immediately as it starts to simmer.

Allow sugar mixture to cool for 10 minutes and then pour over orange juice and leave for 15 minutes.

Strain mixture using a muslin cloth. Pour into a sterilised bottle and place cap on bottle.

Allow to cool and store in the pantry for up to 12 months. Or pop it in the fridge to enjoy immediately.

Enjoy mixed with water or soda water, using 1 part cordial and 4 or 5 parts water.