Lemons are hard to come by In Central America, there are plenty of limes. But today I used sour oranges. Syrup is made from 1/5 cup sugar, 1/2 cup water, zest from 8 sour oranges heated to dissolve the sugar. remove from heat, add juice form those 8 sour oranges and let steep until room temperature. Strain into a jar, close lid and store in fridge for up to 2 weeks. 1 part syrup and 10 (mas o menos) parts chilled sparkling water.