Add the sugar to the mason jar, then add the strawberries and the vodka. Screw on the lid as tightly as possible and shake to combine and until half the sugar dissolves.
Soak for 48 hours, shaking it again on the second day until all the sugar dissolves. Strain through a mesh colander lined with two layers of cheesecloth placed over a bowl. Discard the strawberries and keep the liqueur. Use a funnel to transfer the liqueur to multiple smaller mason jars and screw on their lids. Store in a cool dark place. Will keep in the refrigerator for up to 1 year.