3 ripe bananas
1/3 cup fresh lemon juice
1/2 cup superfine sugar
3/4 cup water
3/4 cup rum

Working quickly to keep the bananas from darkening, peel and place them in a food processor. Purée the bananas with the lemon juice until smooth, then stir in the remaining ingredients. Pour the mixture in the bowl of the machine and freeze, depending on how firm you like your drinks.