There are only three ingredients in a julep: Bourbon, sugar and mint. (Four if you count ice.) The traditional recipe calls for it to be served in a silver or pewter cup, but if all you have is glass,
don't be dissuaded from trying it. You'll also need a short straw, but again, that isn't absolutely
essential.
The single most important ingredient in the julep is the bourbon - if you use rotgut stuff, then it will taste nasty, no matter how much effort you put into preparation. And forget the Jack Daniels. That isn't bourbon at all; it's sour mash, and not fit for a distinguished julep. I recommend
Maker's Mark, or Wild Turkey if MM isn't available. If you can find one, there are some
excellent single barrel bourbons (the bourbon equivalent of single-malt scotch) which are
delightful, albeit a bit expensive.
Place three or four fresh spearmint leaves (the red-stem variety works best) and about a
teaspoon of confectioner's sugar in the cup and add just enough bourbon to make a thin paste. The idea is to dissolve the sugar while "bruising" (gently crushing) the leaves against the side of the cup. Then fill the cup with crushed ice - really pack it in tightly. Fill the cup with bourbon, stir it
to distribute the sugar paste evenly throughout the drink, and garnish with a mint sprig. The last is important, because of the straw - the short straw is designed to get your nose right down into the mint sprig while you're sipping it, as the aroma of the mint adds greatly to the experience.
I have seen other, more foo-foo versions of the recipe, but this is authentic. There was an article
about the drink in the New York Times just before the Derby - April 30, I think - with a couple of
complicated recipes, one of which gave me pause. It called for, among other ingredients, two
ounces of bourbon, and at the end, said that it served six. Now, I don't know whether all you
yankees are such lightweights, but around here, you couldn't offer a gentleman a 1/3 oz. julep
with a straight face and avoid a duel. ((Indeed! I saw the Times article you mention and I was
struck by the same ``lightweight'' portions.))