Take a cocktail shaker and fill half of it with some crushed ice.
Pour in 1 ½ oz of pisco, ¾ oz of lemon juice, 1 oz of simple syrup and albumen of one whole egg.
Cover the cocktail shaker appropriately and shake it energetically for a few seconds until all the ingredients mix well, forming a foamy surface.
Grab an old-fashioned cocktail glass and place a few ice cubes in it.
Remove the lid of the cocktail shaker and gently strain the Pisco Sour Cocktail into the chilled old-fashioned cocktail glass.
Top the Pisco Sour Cocktail with three dashes of Angostura bitters for taste. Serve immediately.