Notes
A Caipirinha is one of the most refreshing drinks I know of. On a hot day, this one is right up there with mint juleps and gin and tonics. It is the national drink of Brazil. There is some work involved in the muddling, but it is well worth it.
I use turbinado sugar instead of white sugar. The turbinado sugar gives the Caipirinha more body and depth. The turbinado crystals are quite substantial, and will abrade the lime skin to release the lime oil. This oil combined with the sugar and lime juice give off an enchanting aroma. Give it a smell before the cachaca and ice go in.
Because of the size of the crystals, turbinado sugar does not like to dissolve. If you are making this drink to drink immediately, add an extra teaspoon of sugar. Some will be left at the bottom of the shaker, and this will get you the correct sugar to lime ratio (about 4 teaspoons to 1 whole lime).
If you are going to pre-muddle a bunch of glasses (if you have a lot of guests to serve) or take your time muddling, use 4 teaspoons of sugar to each whole lime. While they sit, the sugar has a chance to dissolve in the lime juice. Muddle one more time before preparing the drink.
I make my Caipirinhas big in a pint glass. You don't have to muddle as often when you make them this size. Feel free to halve the ingredients to make a smaller Caipirinha if you want: half a lime, 2 teaspoons of turbinado sugar, and 2 oz cachaca. Serve this in a highball or rocks glass.
You can put a squirt of club soda in the shaker before muddling to help dissolve the sugar. If the drink is a little strong for you, top with club soda.