Place frozen peach slices, sugar, and lemon juice in a food processor or blender. Process until it's chopped up well. Stop the machine and scrape the sides.
Add the warm water. Process until smooth, scraping the sides as needed.
Eat immediately for a soft-serve texture, or spread peach sorbet into a shallow freezer-safe dish, press plastic wrap or parchment paper onto the top, and freeze for 3-4 hours, or until firm.
Notes
FRESH PEACHES - You may peel the peaches or leave the skin on if you have a heavy-duty food processor/blender. You may freeze the peach slices on a tray with parchment paper first, or blend them as-is.
*Omit the water if using fresh peaches (not frozen). FYI: Adding water will make the sorbet more icy after freezing completely. It's best to eat the sorbet just after blending, if using frozen peaches and water.
Using fresh peaches may take up to 6-7 hours to freeze completely.
You may pour the pureed peach mixture into an ice cream maker to churn, if desired.
Store peach sorbet in an airtight container in the freezer for up to 2-3 months.