Fill your mug with crushed ice. A copper mug is classic and keeps the drink extra cold, but a rocks glass works too.
Add 1.5 to 2 ounces of vodka. Use 1.5 ounces for a lighter drink; 2 ounces for something stronger.
Squeeze in fresh lime juice. About 0.5 to 1 ounce (roughly half a lime). Taste as you go—fresh lime makes a big difference.
Pour in 4 to 6 ounces of low-carb ginger beer. Start with 4 ounces and top off to taste. If using ginger sparkling water, add a few drops of sweetener.
Adjust sweetness and spice. Add 2 to 5 drops of liquid stevia or monk fruit if needed.
For more heat, add a thin slice or two of fresh ginger and lightly muddle.
Stir gently. You want everything mixed, but keep the fizz.
Garnish and serve. Add a lime wedge and a fresh mint sprig. Serve immediately while it’s icy cold.