To a medium-sized saucepot add granulated sugar, water, sliced strawberries, and basil leaves. Stir to gently combine.

Set over medium heat.

Bring to a simmer and cook until the strawberries are mushy and the syrup has thickened, about 15 minutes.

Remove from heat and let it cool down. 

Over a fine mesh strainer, strain the simple syrup, add to an airtight container or jar and keep in the refrigerator for up to a week.