Put the fruit, lime juice and sugar (and salt if you are adding it) into the blender or food processor with a blade attachment.
Blend together until the mixture is smooth.
Pour the puree into the metal pan. Be sure that the layer is not too thin, or it will stick to the bottom of the pan, or too thick, as it will take too long to freeze.
Put in the freezer for 30 minutes.
Remove the pan from the freezer, the puree should have started to freeze on the top and around the edges.
Using a fork, gently scrape the mixture, stir and then put it back in the freezer. After another 30 minutes, scrape again, stir and return to the freezer. Do this every 30 minutes for four hours until the puree is completely frozen and looks dry and flaky like a slushy.
If you want to use a topping such as lime or lemon zest or pepper flakes, prepare them in a separate small bowl and set aside.
Now you can scoop your crunchy fruit granita into small single-serving bowls or cups and add the toppings for extra goodness before serving.