Citrus PeelsJerry Thomas's 1862 Bartender's Guide is the only surviving reference to citrus peel garnishes. But, the guide makes no mention of the technique to follow. So, one can safely assume that the practice was not in widespread use at the time.
Citrus fruits store most of the scent compounds on the skin hence the widespread use of the citrus peels. Twisting a citrus peel releases aromatic oils.
The big debate is whether the peel should be dropped into the drink or twisted over the drink and discarded. The consensus by mixologists is that the peel should be dropped into the drink. This allows a small amount of the aromatic oils to dissolve in the alcohol while a small amount rises to the top which improves flavor. To avoid pesticide residue, dust and other impurities being introduced into the drink, the fruit should be washed in warm water before use.
Olives, Cherries & OnionsUsing olives, cherries and, onions as garnishes date back to the 1800s; the original garnish cherry was the maraschino cherry from Croatia. It was imported to the rest of Europe and the US while preserved in maraschino liqueur. However, the importation costs became prohibitive and bartenders soon began using locally grown cherries and other liqueurs.
Cherries add sweetness to most traditional cocktails but if you can't get cherries, add a single shot of maraschino liqueur or simple syrup for balance.
On the other hand, olives and onions add a slightly salty flavor to various classic beverages. If you find yourself with an unbalanced drink, try a drop or two of salt tincture if you don't have any olives or onions.
Get MixingNow that you know why and how cocktails are garnished, why not mix yourself a drink? How about trying out the only cocktail named for its garnish? It's called the Horse's Neck. When prepared correctly the peel of a whole lemon spirals around the entire glass from top to bottom. Drinker's in the late 19th century, probably while tipsy, thought this resembled a horse's neck hanging into the drink.
You will need 2 ounces of bourbon, 4 ounces of ginger ale and a whole lemon peel. Peel the lemon in one continuous motion starting at one end and working your way around so that you end up with a spiral peel. You may need to experiment with several lemons to get the spiral right. Place the lemon peel into a Collins glass. Add ice cubes and pour all the ingredients into the glass. Stir and enjoy!