Chilean pisco sour — the 3:1:1 ratio with pica lime

The rule is 3:1:1: three parts pisco, one part lime juice and one part syrup or sugar. Per glass, 60 ml pisco, 20 ml lime and 20 ml syrup. It is stronger and less sweet than bar recipes at 2:1:1; if you prefer it softer, drop the pisco to 50 ml without touching the rest. What never changes is that lime and sweet go in equal parts: that keeps the drink balanced, neither sour nor cloying.

The Chilean one uses Chilean pisco (from muscat grapes, more aromatic, 35-40°), pica lime (tiny and very tart) and syrup, and in Chile it traditionally carries no egg white: the foam comes from the shake. The Peruvian one uses Peruvian pisco (drier, 40-42°), key lime, always egg white and Angostura bitters on the foam, also 3:1:1 but with more egg white. Both are good; this recipe is the Chilean one, with the egg white as an option.

Yes, and it is the most traditional way in Chile. The foam comes from the lime juice shaken hard with the ice; it lasts less than an egg-white foam, but it is clean and does not change the taste. For a dense foam without egg, add 2 tablespoons of aquafaba (the liquid from a can of chickpeas) per 4 glasses: it foams like egg white and is vegan.

The shaker gives a cleaner, colder drink with a fine foam and no ice inside: the bar version. The blender is the home and fonda version: faster for many glasses, with abundant foam and a little crushed ice that makes it more refreshing and slightly softer. For 4 glasses both work; for 20, the blender in batches of 4-6 glasses is the practical choice.

A clear Chilean pisco at 35° or 40°; 35° gives a softer drink and 40° a drier one with more body. There is no need for an aged or 'guarda' pisco: its oak is lost behind the lime. Higher-proof piscos (43°-46°) work but call for a smaller dose, 50 ml. Keep the bottle in the freezer before a party: it does not freeze and it chills the drink without diluting it.

Mix in a pitcher 750 ml of pisco (one bottle), 250 ml of lime juice and 250 ml of syrup, cover and keep in the fridge for up to 4 hours: that is the base for 12 glasses. To serve, shake every 4 glasses (320 ml of mix) with ice in the shaker or blender so the foam forms; without shaking with ice it is not a pisco sour, just pisco and lime. Egg white and bitters go only in the shake, never in the pitcher.