Blend all the ingredients except the seeds, till smooth. Pour into a metal container, cover and freeze till set.
Take the Gelato out and run it till smooth in your food processor to break the crystals. Scrape back into the container and freeze till set. Once again run in the processor till smooth. Mix in the seeds and return to the freezer.
If the Gelato has set very hard, take it out of the freezer and refrigerate it for an hour to soften. Serve with sauce and toppings of your choice. Fresh chopped mango and passion fruit sauce are excellent choices.