This is from David Wondrich as printed in Esquire.
Ingredients
mint
1 teaspoon sugar
3 ounces bourbon
Glass Type: old-fashioned glass
Instructions
(Representing the High Kentucky School of Julepistics)
Place 5 or 6 leaves of mint in the bottom of a prechilled, dry 12-ounce glass or silver beaker. Add sugar and crush slightly with a muddler. Pack glass with finely cracked ice. Pour a generous 3 ounces of Kentucky bourbon over the ice. Stir briskly until the glass frosts. Add more ice and stir again before serving. Stick a few sprigs of mint into the ice so that the partaker will get the aroma.
Still not enough mint flavor? Try this: For each julep, lightly cover about 10 sprigs of mint with superfine sugar, add an ounce of spring water, macerate, let stand for 10-15 minutes, and strain through a fine sieve into the ice-filled glass. Then add whiskey and proceed as above. If you'll stoop to maceration, you might also want to float 1/2 ounce of dark Jamaica rum on top.
In the dark backward of time, the Proper Construction of the Julep, like the Beauty of My State's Women and the Timing of Pickett's Charge, was one of those topics that an American male with social aspirations was expected to regard as a matter of honor -- at least, if said specimen was a son, nephew, cousin or acquaintance of the South. Just about every state in Dixie had its own sacrosanct way of handling the mint, the sugar, the ice, the booze. Duels were fought. Names were called.
Brushing aside all the tedious to-and-fro about brandy, rum, and rye (before the War between the States, a true southern gentleman would be hanged before he'd let whiskey pass his lips, and even after, when standards had slipped, no Marylander would build his julep with anything but rye), it's that mint that caused most of the trouble.
At the beginning of the twenty-first century, the Mint Question is as the "filioque" debate that so exercised medieval theologians -- moot, moot, moot. Hypersweetened iced tea and Coca-Cola have taken the mint julep's place as the Grits Belt's summer cooler of choice. Whether you muddle the mint or slide it into the glass altogether unmolested matters as much to the vast majority of southern manhood as whether the Spirit proceeds from the Father to the Son or the Father and the Son.
Ecumenical to the quick, we'll take our communion from either school without scruple.
Whatever your denomination, here are a few things to keep in mind:
1. Use a prechilled, dry 12- or 14-ounce glass, tall and slim (better yet, of course, the traditional silver beaker).
2. Crack the ice, making sure to drain off any excess water before putting it in the glass.
3. Don't handle the glass with bare hands, as the touch of a hand kills the frost. Likewise, each julep should be served with a napkin or small linen doily.
4. The glass will not frost if in the wind, if wet, with undried ice or if excessively handled. You can sometimes speed the frost by twirling the glass or by placing in coldest part of refrigerator for about 30 minutes.
5. Use only the freshest mint and, of that, the smallest, most tender leaves.
6. If you use a straw, keep it short so you can get your nose in among the mint.
I myself prefer higher strength Bourbon's as there is a lot of crushed ice to dilute it. George T Stagg makes a most excellent julep. I usually add a dash or two of Peychaud's bitters but I loves me some bitters.
