Put the crushed ice, rum, passion fruit juice and lime juice in a cocktail shaker and shake well. Pour the cocktail into a long drink glass filled with some crushed ice and, if the cocktail tastes too strong, add a little juice, depending on your taste.
Finally, add the grenadine over a tablespoon so that it settles nicely on the bottom of the glass. The sunset is done.
If necessary, the long drink glass can be garnished with a slice of orange or other pieces of fruit.