Sous vide:
Vacuum all ingredients in a sous vide bag and cook sous vide in a fusionchef sous vide water bath for 10 minutes at 50 °C. Quench the liquid in ice water and strain it through a paper filter.

Cocktail:
Fill all ingredients into a mixing glass and stir until cold. Strain the liquid in to a tumbler filled with ice cubes.
Squeeze the zest of grapefruit above the drink and then drop it into the glass.

This recipe was generously provided by Andreas Till.