Add Irish whiskey and stir in brown sugar until dissolved.
Add fresh lime juice and mix gently.
Slowly top with ginger beer to keep the fizz.
Stir lightly with a cocktail spoon.
Garnish with a lime wedge and mint sprig.
Notes
Strong coffee stands up to ginger beer. Adjust whiskey and ginger beer for strength. Always use fresh lime juice and garnish for best flavor and aroma. Serve hot, or over ice for a chilled version.