- Wash the green tomatoes well; peel and slice.
- In a saucepan, combine tomatoes with lemon juice, lemon zest, salt, and cinnamon. Cook the spiced tomato mixture over low heat, stirring frequently.
- Combine sugar and cornstarch; stir into tomato mixture. Cook mixture until clear, stirring constantly. Add butter, remove from heat, and let stand until slightly cooled.
- Line a 9-inch pie plate with pastry; pour in tomato mixture. Cover with top pastry, seal edges, crimp, and cut several small slits in crust to allow steam to escape.
- Bake at 425 F for 35 to 45 minutes, or until nicely browned.
Serve warm or cooled.