Sitr first three ingredients with ice, strain into Fernet-rinsed coupe, spank the mint lightly and set it in the glass, half on the rim.
*To make mint syrup: Boil one cup of water in a pot; turn heat to low and slowly add one cup of granular sugar; stir to dissolve. Turn off heat, then add 20 fresh mint leaves. Let steep 20 minutes. Strain syrup and let cool, then pour into bottle. Add half an ounce of overproof vodka, cap bottle and refrigerate. Keeps for at least a month.