The ginger gives this sorbet a little extra bite.
Cube pears and sprinkle with lemon juice. Place in a medium saucepan along with ginger. Cook over medium heat for 10 minutes, stirring occasionally. Add sugar and water and cook, stirring constantly, until sugar has dissolved.
Let pears cool slightly, then puree. Transfer to a bowl and cool in an ice-water bath. Freeze in an ice-cream maker according to manufacturer's instructions.