So, it's pretty self-explanatory... You can do it in a food processor, or with a pestle and mortar, or just with a knife if that's all you've got, doesn't matter
What you will need
fresh mint leaves (between 3 and... a lot, depending on your desired level of mintyness)
1 cup sugar
strawberries, for eating your mint sugar with!
For the food processor (or stick-blender things), just toss in the sugar, and start small with the mint, adding more as you go until you're happy. With the pestle and mortar, chop the mint first, then grind it, slowly adding sugar to the mix until it's un-clumpy enough to mix it with the remaining sugar. With a knife, chop it as small as you can sanely do, and then add the sugar in the same way as with the pestle and mortar. Grab a pile of strawberries, or pineapple, or add it to a cocktail. Do whatever you like with it, just enjoy it! Oh, and I freeze some in smaller containers so I can still have my precious Mint Sugar long after I kill my mint plant!