Even though we San Franciscans are chilly most of the year, during these rare scorching days of summer, it's hard not to occasionally fantasize about a cold beverage, filled to the top with glistening, frosty ice cubes. We don't usually spend a lot of time thinking about ice, but I can assure you that many of city's bartenders do whether it's cubed, spheroid, chipped, shaved or crushed.

All ice is not created equal. Minerals and trapped gasses in the water are enemies of the perfect cube, both aesthetically by making it cloudy but also preventing it from getting as cold as possible. But starting a couple of years ago, several of the city’s better bars have been infiltrated by ice machines by Kold-Draft Industries, an Eyrie, Pennsylvania based company that has been making large (though not huge), clear, extra-cold ice cubes since 1955. At the Alembic, several oversized cubes will chill down anything from a gin and tonic to an old fashioned. Because of its bigger size, the ice melts more slowly, cooling the cocktail without overly diluting it.

At Heaven's Dog, GM Erik Adkins has taken the opposite tack, making giant cubes (almost filling their egg-shaped rocks glasses) for their whiskey drinks. “Ice makes  a difference. I’ve heard that in Japanese businessmen will sit with a giant cube and drink one whiskey over an hour,” he says. Adkins tells me that the easiest way to get the purified water they use to make clear ice, is to melt down the ice from their Kold-Draft machine and re-freeze it into a giant block that they then attack with picks and saws. I always finish my drink at HD faster than the gorgeous shards of ice can melt, giving me a slight guilty feeling for leaving them behind. Is it silly ask for a doggy bag for an ice cube?

The Mint Julep is one of the most refreshing cocktails there is and a perfect vehicle for crushed ice.

3 sprigs of mint
1/2 ounces simple syrup or 1 teaspoon superfine sugar
2 ounces bourbon
crushed ice

In the bottom of a highball glass add 5 or 6 mint leaves and the simple syrup or sugar. If using sugar, add a dash of water. Gently tap the mint a few times with a spoon or a muddler. Do not crush it, as that can make the mint bitter and cloying. Fill the glass with crushed ice and pour the bourbon over it. Garnish with a full sprig of mint and a spoon, for stirring the drink as the ice melts. You can put this drink in tall glass, as well and top it with soda for a long cocktail, a sort of bourbon mojito.