Simmer the pears, water, and sugar in a saucepan for 8 minutes, until soft.

Cool for 10 minutes, then blend with the lemon juice and zest.

Chill the mixture for 1 hour.

Freeze it in an ice cream maker. If I skip that step, I freeze it in a shallow dish and stir every 30 minutes for 2 hours.

Freeze until firm, then let it sit at room temperature for 5 minutes before scooping.