Tumbo Sour

the Andean cousin of the pisco sour: the sharp highland tumbo replacing the lime, shaken with pisco, syrup, and egg white to a thick white foam and dashed with bitters

Origin: Peru

From the journey of Passion Fruit.

The pisco sour is the great cocktail of Peru, built on pisco, the clear grape brandy of the coastal valleys, sharpened with lime and given its characteristic thick white collar by shaken egg white. The tumbo sour is its highland variation, and in Peru and Bolivia it is regarded as the more interesting drink. The tumbo, called curuba in Colombia and taxo in Ecuador, is the banana passionfruit of the Andes, a long, soft, yellow fruit of the cool uplands whose pulp is so sharply acidic that it is never eaten raw. That acidity is exactly what a sour requires, and it brings with it a floral, almost tropical perfume that lime cannot supply, so that the drink is at once bracing and fragrant, pale gold beneath its foam. There is a deep local logic to it: long before the Spanish brought limes and grapes to the Pacific coast, the peoples of pre-Incan Peru were using the juice of the tumbo as a souring agent, most famously to cure raw fish in the distant ancestor of ceviche. The tumbo sour puts the oldest acid of the Andes back into the country's most famous modern drink.

Ingredients

Cocktail

  • 60 ml pisco
  • 30 ml tumbo (banana passionfruit) pulp, sieved
  • 20 ml sugar syrup (equal parts sugar and water, dissolved)
  • 1 whole egg white

Garnish

  • 3 drops Angostura bitters, to finish

Method

  1. Scoop the tumbo pulp into a sieve set over a bowl and press it through with a spoon to extract the juice, discarding the seeds. You need about 30 ml of smooth pulp.
  2. Put the pisco, sieved tumbo pulp, sugar syrup, and egg white into a cocktail shaker without ice and shake hard for about 15 seconds.
  3. Add a good handful of ice and shake again, hard, for a further 15 seconds, until the shaker is thoroughly frosted.
  4. Strain into a chilled coupe or short tumbler, leaving the ice behind. Let the foam settle for a moment into an even white cap.
  5. Drop three dashes of Angostura bitters onto the foam and, if you like, draw a cocktail stick through them to trace a pattern. Serve at once.

Notes

The classic proportions of a Peruvian sour are three parts pisco to one part acid to one part syrup; adjust the syrup to the sharpness of your fruit, as tumbo varies considerably. Peruvian pisco is unaged and aromatic and is the proper spirit; a Chilean pisco or even a clean white spirit will work at a pinch. Those wary of raw egg white can use pasteurised white or aquafaba, which foams nearly as well. The same drink made with maracujá pulp is the maracuyá sour, equally popular in Lima.

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