Dry (real) Pisco Sour. 3 parts of chilled Peruvian pisco (never use the Chilean liquor; only Peruvian: half Italia, half Quebranta or Acholado), 1 part of lime juice (the small green Peruvian or Central America acid lemon, gently squeezed), 3/4 part of gomme or sugar syrup, 1/2 part of egg white. Shake well, without ice cubes. Pour over ice cubes; leave it in the ice glass for three minutes. Serve on a chilled glass without the ice. Float some drops of real Angostura bitter and enjoy it.