1 1/2 cups granulated sugar
1 1/2 cups water
1 1/2 cups freshly squeezed lemon juice (juice of 8 to 10 lemons)
Peel of 1 lemon, cut into fine slivers (yellow part only)
In a 3-quart microwave-safe dish, combine sugar and the water. Microwave on HIGH until mixture boils and sugar dissolves (6 to 8 minutes), stirring every 2 minutes. Let cool completely.
Stir lemon juice and lemon peel into cooled syrup. Pour into a clean jar, cover, and store in the refrigerator.
For each serving, in a 12-ounce glass combine 1/2 cup lemon syrup and 1/2 cup water. Fill glass with crushed ice and serve immediately.
For lime syrup, substitute the juice of 12 limes and the peel of 4.