Engineering The SourSimply put a Sour is a drink consisting of a base liquor plus a sour component balanced against a sweet component. A Daiquiri uses rum lime and sugar. A Bee's Knees calls for gin lemon and honey syrup. A Margarita mixes tequila lime and orange liqueur. The basic formula for a Sour is 2 parts of the base spirit to 1 part of the sweet component and 1 part of the sour component.For example:Daiquiri 2 parts white rum 1 part simple syrup 1 part fresh lime juiceShake ingredients with ice and strain into a cocktail glass or strain onto new ice in a rocks glass.Cocktail recipes and definitions change with the times (just like language) so we re taking a broad and modern view of a Sour here. At one point a Sour always called for lemon juice not lime. At a later point Sours usually had egg white added to them to give them a frothy head. Heck a better name for this drink format would be the Sweet-and-Sour so let s not get too hung up on that.Regardless with this basic recipe we can swap out ingredients and plug in others but the sweet-to- sour balance is the key. As Attaboy bartender Sam Ross says “The sweet and sour elements in a cocktail are like the pieces of bread in a sandwich. If they re not in balance the whole thing falls apart.”The sour component of a Sour is usually lemon or lime juice but it can be grapefruit or yuzu juice or even muddled sour candy if that s how you roll. The sweet component can be anything from a non- alcoholic sweetener like simple syrup agave nectar and grenadine to a liqueur like Cointreau or peach schnapps. It could even be an artificial sweetener like Sweet ‘N Low though most bartenders would argue against that choice.Then we can throw in anything else to the drink that doesn t alter that sweet-to-sour balance. Egg whites are still used in vintage-style Whiskey Sours and all Pisco Sours to give them a nice foamy head and softer texture. Herbs and spices and bitters can provide accents as well.Pick one of each and get started:Base spirits: Vodka gin tequila brandy/cognac rum pisco bourbon rye scotch cachaca etc.Sour elements: Lemon juice lime juice grapefruit juice yuzu juice (make sure it s unsalted). Note that orange juice and pineapple juice are rather sweet so if you use those you ll also want a sour juice in the drink as well. Most bartenders use lime.Sweet elements: Raw sugar simple syrup (equal parts sugar and water) agave syrup (equal parts agave nectar and water) honey syrup (equal parts honey and water) maple syrup etc.Extras: Herbs (mint basil oregano etc.) spices (cinnamon nutmeg black pepper hot sauce etc.) egg white garnishes (citrus zests cherries etc).That 2:1:1 ratio ( 2 parts base spirit to 1 part sour to 1 part sweet) can change depending on a bar s house style. A neighborhood bar might make drinks with a little less booze; while a modern speakeasy-style cocktail bar might emphasize the spirit by reducing both the sweet and sour. Some people like their Sours on the sweet side while others may take a citrus-forward approach. Start with 2:1:1 proportions find the balance that you like and go forth and make many cocktails.A note on sweeteners and sours: Some people use sweeter simple syrup than others †start with equal weights of sugar and water to make simple syrup (no need to heat it; it will dissolve if you're patient). When using thick agave nectar or honey dilute it with equal parts of water. Keep in mind that lemons and limes are not the same sourness as each other and they also change in tartness over the season. You ll need to adjust the quantities to keep the drink in balance.• The Cosmopolitan is actually a clever variation on the Sour with citrus vodka triple sec lime juice and cranberry juice (which is both sweet and slightly tart) which requires rebalancing the other ingredients.• Add soda water or another unsweetened filler to a Sour and you ve got a whole new group of cocktails at your disposal (known as the Collins). A Mojito is a Rum Collins with Mint which in turn is just a Daiquiri with soda water and mint. A French 75 is a Gin Sour with champagne as the filler. If you use a sweetened soda like ginger beer as a filler you ll need to reduce or eliminate the other sweet component.• You can also use a sweet liqueur for the base spirit (as in the Amaretto Sour) but then you ll want to seriously reduce the amount of the sweet element to rebalance the drink.