Put equal parts sugar and water into a saucepan (1 C. each is a good amount) and bring it just to the point of a light boil, when bubbles start to rise and the liquid clarifies, you’re done. Drop a handful of mint into the pot and give it a quick stir. You want the mint to brighten up and come alive, but not wilt or brown.
Put the warm mixture into a blender and purée.
Strain into a jar or bottle using a funnel.