Pour two ounces of vodka into the glass. You can build this cocktail in the same glass that you'll serve it in.
Pour 3-4 ounces of ginger beer into the glass. You don't have to be precise with this measurement. Pour until the glass is about three-quarters of the way full, which will leave enough room for ice.
Squeeze the juice from half a lime directly into the glass. While fresh lime juice is definitely the best, a tablespoon of lime juice from a bottle will do.
Add ice. The drink is traditionally served with crushed ice, which you can make in your blender. Add a scoop of this, or a few regular ice cubes if you want to keep things easy. Garnish with a lime wedge cut from the other half of your lime and serve.