Authentic grenadine syrup is made from pomegranate juice sweetened with sugar and flavored with a few drops of lemon juice and orange-flower water (as opposed to corn syrup and red dye). Once you taste the real deal in, say, a Mary Pickford, you’ll never go back to the Shirley Temple cocktail mixer of your youth.
1Heat pomegranate juice in a small saucepan over medium heat until steam rises from the surface and a few bubbles have formed around the perimeter of the pan, about 5 minutes. (Do not boil.) Remove from heat.
2Add sugar and stir until it has dissolved and the liquid is no longer cloudy, about 5 minutes.
3Stir in lemon juice and orange-flower water and let the syrup cool to room temperature, about 40 minutes. Transfer to a container with a tightfitting lid and refrigerate for up to 1 month.