What is Espresso?

Espresso is coffee extracted under pressure in a short time, yielding a concentrated shot with crema. In the Espresso Martini the shot is an ingredient alongside vodka and coffee liqueur, shaken hard so proteins and emulsified oils form a foam. Instant espresso, reconstituted strong, can approximate the solubles in a pinch; drip coffee is too dilute and usually too stale.

Cold brew is a different extraction (long, cold, lower acidity) and will not automatically reproduce the same foam or roast character.

Roast, crema, bitterness, and a little sweetness from the bean’s sugars. Stale or over-extracted diner coffee produces a muddy, ashy martini. The crema and dissolved CO2 contribute to the foam when the drink is shaken with ice; that foam is not dairy.

The Espresso Martini is attributed to Dick Bradsell in late-20th-century London: vodka, coffee liqueur, and a fresh espresso shot, shaken. The foam is a consequence of agitating hot or freshly pulled coffee with ice — dissolved gases, coffee oils, and protein — not a cream float.

Coffee in mixed drinks is older (rum and coffee, coffee liqueurs), but this particular short, shaken template is modern.

Pull the shot and shake immediately so the coffee is still fresh and the crema has not collapsed. Too much liqueur and not enough coffee is how the drink becomes dessert; the shot should be audible as coffee, not only as sweetness.

Shake hard with ice; strain. A dry-shake is unnecessary; the espresso already supplies foam-forming material.