Why a Penicillin has smoke on top: the spec, the honey-ginger syrup and a builder

The Penicillin is a Scotch sour with honey, ginger and a smoky finish. It was created in 2005 by Sam Ross at Milk & Honey in New York, and it is one of the few drinks from the cocktail revival that people now treat as a modern classic. It works because every ingredient does a different job, and one of them, the smoke, is barely there at all.

The spec

Recipes differ in small ways. This is the common version, close to the one usually credited to Ross, in ml with ounces in brackets.

Method: shake the Scotch, lemon and syrup hard with ice, then strain over fresh ice. Float the Islay whisky on top by pouring it slowly over the back of a spoon. Glass: a chilled old fashioned (rocks) glass, ideally with one large cube. Garnish: a piece of candied ginger on a pick.

Build it yourself

Set the number of drinks, switch between ml and oz, and slide the lemon and the syrup to see how the balance moves. The rule of thumb behind it is the sour template, roughly 3 parts spirit to 1 part sour to 1 part sweet. Here the sweet is also the spice, so it is worth tasting before you pour.

Why it works

A Penicillin is a whisky sour in disguise. The Scotch is the base, lemon brings acid, and the syrup brings sugar, so the drink is balanced the way every sour is: sweet and tart held against each other with spirit underneath.

The twist is that the sweet part is also the spice. Ginger is simmered into honey, so one ingredient adds sweetness, warmth and a peppery bite. That is also why the drink feels soothing on a cold evening, although it is a cocktail and not a remedy.

The smoke is the last piece. A blended Scotch is mild and slightly sweet, which lets honey and ginger show. A small float of peated Islay whisky sits on the top of the glass, so the first thing you smell is smoke, while most of the drink underneath stays soft. That is why only 7.5 ml is used: a little is a perfume, a lot is a different drink.

Honey-ginger syrup

The syrup carries the drink, so it is worth making it properly. A common version is roughly equal parts honey and water, simmered with sliced fresh ginger for about five minutes, then left to steep as it cools before straining. Some bars use a thicker honey syrup (about three parts honey to one of water) and add ginger separately, so the strength varies. Taste yours: if it is very sweet, cut it back in the builder above.

The syrup is made from fresh ingredients, so keep it in the fridge and use it within a few days. A runny, mild honey works fine. Save a strongly flavoured one, like heather or chestnut, for drinking straight.

Variations, including alcohol-free

• No Islay float. Leave it out for a softer, honeyed version.
• Extra ginger. Muddle two or three thin slices in the shaker, or add a little ginger liqueur. Taste before you add more.
• Alcohol-free. Replace the Scotch with 60 ml of strong, cooled lapsang souchong tea, a black tea that is dried over pine smoke. It has the smoke and a tannic grip a little like an oak-aged spirit. Keep the lemon and syrup, skip the float, shake with ice and taste: you may want slightly more lemon. Tea contains caffeine, so go easy late in the evening.
• Hot. Warm the tea or hot water with the syrup and lemon in a mug for a cosy non-alcoholic drink.

Serve it well

Use plenty of ice in the shaker and shake hard for about 10 to 15 seconds. Strain over fresh ice, because the ice in the shaker is already broken and will water the drink down. A large cube melts slowly, so the last sip stays close to the first. Enjoy it slowly, and drink responsibly.