Heat 1 cup water to just under a boil. Pour into bowl along with a few sprigs rosemary (bruise first). Allow to steep for 10 minutes. Strain water back to the pot and add 1 cup sugar. Heat over medium heat, stirring continuously until sugar is dissolved. Allow to cool. This can be stored in fridge up to 1 week.
Fill cocktail shaker two-thirds with ice. Add vodka, lemon juice and simple syrup. Shake to thoroughly chill -- then shake some more! Strain into martini glass. Garnish with lemon peel and/or rosemary sprig. Slurp away!