1. Place berries in the work bowl of a food processor and puree until smooth.
2. Combine berry puree, sugar, and salt in a large saucepan. Heat until melted and just simmering. Whisk cornstarch into the cold water; stir into heated berry mixture. Remove from heat, and stir in lemon juice. Cool slightly.
3. Refrigerate berry mixture until cold, about 2 hours.
To freeze this sorbet without an ice cream maker; pour strawberry mixture into a shallow dish, place dish in freezer, stir occasionally until sorbet reaches desired consistency.