In a large saucepan, combine the cornstarch and ginger. Stir in the water, corn syrup, lemon juice and zest until smooth. Gently stir in pears. Bring to a boil over medium heat; cook and stir for 1 minute or until thickened. Remove from the heat; add butter. Pour into pastry shell.
For topping, combine the flour, brown sugar and ginger in a small bowl; cut in butter until crumbly. Stir in pecans. Sprinkle over pears. Bake at 425° for 20-25 minutes or until filling is bubbly and topping is browned. Cool on a wire rack.