To make the dough: In a large bowl, combine the flour, sugar, and salt. Working quickly, incorporate the butter until the mixture resembles small rocks. With a fork, add ice water, 1 tablespoon at a time, until the mixture holds together. Shape into 2 flat disks, wrap in plastic wrap, and refrigerate for 1/2 hour.

To make the filling and tart: To make the lower crust, roll out the dough and place it in a tart pan. In a small bowl, mix the egg with the water and apply a thin layer to the crust. Refrigerate the lower crust while preparing the filling. In a large bowl, mix the sugar, instant tapioca, lime juice, ground ginger, salt, lime zest, and nutmeg. Add the raspberries and mix gently to coat. Let the mixture sit for 5 minutes. Remove the crust from the refrigerator, pour the raspberry mixture onto the lower crust, and dot with butter. Brush the edges of the lower crust with the egg mixture, then place the second crust on top. Seal the edges and make several cuts in the top crust. Refrigerate the tart for 20 minutes. Preheat the oven to 425°F. Brush the top with half-and-half and sprinkle with sugar, if desired. Bake for 15 minutes, reduce the temperature to 375°F, and bake for 25 minutes or until golden brown.