1. Add the frozen fruit and sweetener (and lemon juice, if using) to a high-powered blender or food processor, and begin pulsing the mixture to break it up, before running the processor on low for 1 minute. If things do not seem to be moving much, add a tablespoon or two of water and run the processor again. Once things start blending up smoothly, turn the processor to medium-high and run for a minute or two, stopping every so often to scrape down the sides with a spatula. After a few minutes, everything should be smooth and creamy like ice cream. Serve immediately, or pour into a freezer-safe container and place in the freezer for 3-4 hours before serving.

If freezing the sorbet longer than 4 hours, you may need to let it sit out at room temperature for a few minutes before scooping and serving. Sorbet will keep for up to 1 week in the freezer, or longer.