How to Make a Genuine Cuban Mojito
To make a genuine Cuban mojito, start by adding mint sprigs, sugar, fresh lime juice, and lime wedges to a tall glass. Then, pour sparkling water into the glass, and use a wooden muddler or spoon to gently twist and bruise all of the ingredients to release their flavors. Finally, add 1 part rum for every 2 parts sparkling water you used, and top your drink off with some ice cubes.
Find or order fresh hierbabuena mint. Also known as yerba buena, this mint has a citrus flavor and only a hint of mint. Unlike other mints like spearmint or peppermint, the flavor comes predominantly from the stems and not the leaves. If you're going for authenticity, you may want to grow it yourself or order hierbabuena from Cuba. If you can't track down any hierbabuena (you may not be able to if you live in the US), substitute with spearmint instead. It is important to note that if you use spearmint, you do only want to use the leaves, not the stems. Muddling the stems will make give your Mojito a bitter taste. Cut half of a large, fresh lime into four wedges and squeeze the juice into a small bowl. Do not throw away the lime wedges, as you will still be using them in your drink. The smaller pieces will fit in your glass better and be easier to muddle. Hang on to the other half of the lime. No two limes have the same amount of liquid, so you may need it to add a little more juice later. You can also use the remaining lime as a garnish, cutting it into wedges or a wheel. Pick a high-quality, white rum. For a genuine Cuban Mojito, you will of course want a premiere Cuban rum. It follows that the better the rum, the better the Mojito. If you are unable to obtain Cuban rum (this will be difficult to get if you live in America), substitute an aged white or silver rum instead. Use a fine, granulated sugar. It is difficult to dissolve sugar in cold liquid, so you may have a rather gritty drink if your sugar is too coarse. If you can't find a fine sugar or prefer Turbinado sugar (which only comes in a coarse grind), you can use a coffee or spice grinder to make the granules smaller. Some bartenders and recipes may recommend substituting simple syrup for granulated sugar, but the sugar plays an important part in muddling the mint leaves. This addition also deviates from the traditional method of Mojito-making. Put the mint sprigs, sugar, fresh lime juice, and lime wedges into at tall glass. You'll want to layer your ingredients this way to protect the mint from becoming over-muddled. Make sure you are using a sturdy glass--a glass with thin, fragile sides could break or chip when you begin muddling. You may be tempted to use a short glass, worrying about a watered down drink, but this is a mistake. Not only will a short glass be overcrowded and awkward, but it defeats the purpose of the mojito: to be sipped and savored. Make sure there is enough lime juice to completely cover the sugar in the bottom of the glass. If it's not quite there, squeeze some juice from the other half of the lime until it's covered. Pour the sparkling water to the glass. Muddling the ingredients with the sparkling water will help infuse the entire drink with the complex flavors of the mojito. Club soda and sparkling water can add to that complexity--if you can find a mineral or sparkling water local to Cuba, it's going to give you the most authentic flavors (sparkling water tastes different depending where it came from, as different springs will have different concentrations of minerals). Club soda will give your drink the right amount of carbonation, and is relatively tasteless, so it won't interfere with the flavors of your cocktail. Just make sure it's not flavored! Place the round end of a wooden muddler in the glass and press down, twisting gently. The point of muddling is not to pulverize, shred, or destroy the mint and lime wedges, but to bruise them enough so they release their flavors. The abrasiveness of the sugar will help gently break down the other ingredients. You will see any remaining juice escape from the lime, but be careful not to press to hard and smash the white pith of the wedges. Your drink can quickly become too bitter if this part of the lime is overworked or broken. Try to concentrate on muddling the stems of the hierbabuena and not the leaves. However, if you are using spearmint, make sure there are no stems in your drink and that you don't tear the leaves too much, or they will release bitter chlorophyll. If you don't have a muddler, you can use a wooden spoon or the handle of a rolling pin instead. Add rum to the glass and top with ice cubes. The proportions should be 1 part rum to 2 parts sparkling water. You can garnish with a lime wedge or an extra sprig of mint. Crushed ice may cool your drink faster, but it will also water it down, so stick to cubes 
Find or order fresh hierbabuena mint. Cut half of a large, fresh lime into four wedges and squeeze the juice into a small bowl. Pick a high-quality, white rum. Use a fine, granulated sugar. Put the mint sprigs, sugar, fresh lime juice, and lime wedges into at tall glass. Pour the sparkling water to the glass. Place the round end of a wooden muddler in the glass and press down, twisting gently. Add rum to the glass and top with ice cubes. 