Cut the apples, bananas, kiwis and grapes into bite-sized pieces and mix in a bowl.
Halve the lemons and extract the juice. Dissolve the sugar in the lemon juice to taste. Pour the juice over the fruit and mix carefully again. Season to taste with the rum.
Spread a few walnuts on the fruit salad and serve.
Tip: Also tastes good with whipped cream, vanilla sauce and raisins.