4 to 5 tonic water Ice Cubes (recommended: Schweppes) (see Note)
3 ounces gin (recommended: Plymouth Gin)
4 ounces tonic water (recommended: Schweppes)
1 tablespoon freshly squeezed lime juice
Lime wedge for garnish
Place the ice cubes in a tall, narrow, chilled glass (the cubes should come near the top.) Add the gin, then the tonic water, then the lime juice, stirring well. Garnish with lime wedge, and serve immediately.
Note: To make the ice cubes, simply fill an empty ice cube tray with tonic water, and let the cubes freeze. It takes just a few hours. Covered well, the cubes will remain fresh-tasting in the freezer for at least a few weeks.