Combine water and sugar in a medium saucepan over medium-low heat. Cook until sugar dissolves into a syrup, about 5 minutes.
Add raspberries, chipotle peppers, and salt to the syrup. Blend mixture with an immersion blender until smooth.
Strain 1/2 of the mixture through a fine-mesh strainer to remove the seeds. Use a spatula to aid in passing the puree through the strainer. Discard seeds and repeat with the remaining mixture. Cover and refrigerate for 2 to 3 hours or overnight.
Pour the mixture into the frozen bowl of an ice cream maker and freeze according to manufacturer’s instructions, 15 to 20 minutes. Transfer the sorbet to an airtight container and freeze until firm, 4 hours to overnight. Remove from the freezer about 15 minutes before serving.