In a food processor combine the flour, granulated sugar and salt. Cover and pulse to distribute ingredients. Add butter; pulse until mixture resembles very coarse cornmeal with a few large butter chunks still visible. While pulsing, add the water slowly. Continue pulsing until the water is evenly distributed but don't allow the dough to form into a ball. Transfer dough to a sheet of plastic wrap and gently knead to incorporate any remaining dry bits. Divide dough into 2 uneven balls; one ball should contain two thirds of the pastry ( 21 ounces). Wrap each ball in plastic wrap. Chill dough portions for 30 minutes or until easy to handle.
Roll the large dough portion into a 17x12-inch rectangle. Transfer to a 15x10x1-inch baking pan and trim edges even with sides of pan. Prick the bottom of the dough with a fork and chill until ready to assemble tart. Roll remaining dough portion into a 15x10-inch rectangle. Cut six 1/2-inch wide strips from the long side of the dough. Next, cut 4 more 1/2-inch wide strips that are 9 inches long. Cut as many 1-inch stars as you can with remaining dough, rerolling scraps as necessary. Place strips and stars on a parchment paper-lined large baking sheet. Brush with a mixture of egg and water. Generously sprinkle with Swedish sugar and gently press sugar into surface of dough. Chill while preparing fillings.
Place raspberries in a large bowl; toss with lemon peel and juice. In a small bowl combine granulated sugar, ClearJel, and salt. Sprinkle sugar mixture over raspberries; toss to combine. Set aside.
Place blueberries in a large bowl; toss with lemon peel and juice. In a small bowl combine granulated sugar, ClearJel, and salt. Sprinkle sugar mixture over blueberries; toss to combine.
Preheat oven to 350 degrees F. With the long side of the dough-lined pan facing you, arrange blueberry filling in the upper left corner of the pan, covering about a 6x4-inch rectangle. Spoon the raspberry filling around the blueberries to fill the pan. Place the dough strips over the raspberries, trimming as necessary. Arrange the stars over the blueberries. Bake 1 1/4 hours or until the filling bubbles and the edges of the crust are golden brown. Serve warm or at room temperature.