Deep-Dish Berry Pie

1. In a large bowl, gently toss berries, lemon juice, lemon zest, rum (if using), sugar replacement, flour, and tapioca. Place in a 1 1/2-quart (1.5 l) ovenproof round baking dish. Set aside.
2. Meanwhile, roll out pastry on a lightly floured work surface to 1/8-inch ( cm) thick. Using a sharp knife, cut out a circle 2 inches (5 cm) larger than the baking dish. Set scraps aside. Brush the circle with the egg-water mixture and place, brushed side down, over the baking dish. Stretch the pastry tight (like a drum), pressing the overhanging dough onto the sides of the baking dish. Cover with plastic wrap and refrigerate for 1 hour. Cover and refrigerate remaining egg-water mixture. Cut the scraps into small decorative shapes with little cookie cutters or a sharp knife. Cover with plastic wrap and refrigerate.
3. Preheat the oven to 450°F (230°C), Gas Mark 8.
4. When ready to bake, brush the top with the remaining egg mixture and lightly press decorative shapes on the top. Brush the tops of the shapes with egg mixture. Bake for 15 minutes, then reduce oven temperature to 375°F (190°C), Gas Mark 5. Bake for another 25 minutes, until pastry is golden.
5. Remove from oven and cool on a rack. Serve warm or at room temperature.

*We'd used a sugar replacement that holds up well when baked and has no aftertaste-such as Splenda, One Spoon (both available here on the Net) and Grandma Kate's No-Sugar Sweetener (available by mail, call 1-800-549-3789).