In a small saucepan, combine the water, sugar, and tea leaves.
Bring to a gentle simmer, stirring occasionally until the sugar dissolves.
Turn off the heat, and cover, letting it steep for 5 minutes. Strain and allow to cool.
Store in a lidded glass jar in the refrigerator for up to 2 weeks.
To make the cocktail:
Place the vodka, whisky, and simple syrup in a cocktail shaker with ice.
Shake for 10 seconds.
Strain, and serve in a chilled glass.
Rub the lemon around the rim of the glass and drop it in, if using.
If salting the rim, do it before making the drink. Run a lime wedge over the rim of the glass to moisten it. Invert the glass into the salt, turning it as needed until the rim is coated.