4 kiwis cut into bite-size pieces (about 2 cups)
1 tablespoon chopped fresh mint leaves (optional)
In a small heavy saucepan, stir 1 cup water and the sugar together over medium-low heat until the sugar dissolves. Slowly bring the syrup to a boil; then remove it from the heat and let it cool completely.
Spoon the passion fruit flesh into the cooled syrup and mix together. Stir in the lemon juice. Pour the passion fruit mixture into an 8-inch square baking dish and freeze it for about 30 minutes, or until the mixture is icy around the edges.
Using a large fork, stir the icy parts of the passion fruit mixture into the remaining mixturein the dish. Continue to freeze the mixture, stirring the edges into the center every 20 to 30 minutes, for about 1 1/2 hours longer, or until it is frozen. Using a large fork, scrape the frozen granita into flaky crystals. Cover and keep frozen.
In a large bowl, gently toss the pineapple, papaya, mango, star fruit, and chopped mint, if using. Spoon the mixed fruit into serving bowls, and top each one with a large spoonful of granita. Garnish with the mint sprigs, and serve.