Add vodka or bourbon, cranberry juice, and lime juice.
Stir gently with bar spoon.
Top off with ginger beer. Stir lightly again.
Garnish with cranberries, rosemary sprig, and a lime wedge if desired. Serve cold.
Notes
Use vodka for a bright, crisp drink; bourbon makes it warmer and richer. Use strong ginger beer for spice. Freeze cranberries for garnish that keeps drinks cold without dilution.