Lattice-Topped Strawberry-Rhubarb Pie

Mix flour, salt, and sugar in food processor fitted with steel blade. Scatter butter pieces over flour mixture, tossing to coat butter with a little flour. Cut butter into flour with five 1-second pulses. Add shortening and continue to cut it in until flour is pale yellow and resembles coarse cornmeal with butter bits no larger than small peas (about five 1-second pulses). Turn mixture into medium bowl.

Sprinkle all but 1 tablespoon of the ice water over mixture. With blade of rubber spatula, use folding motion to mix. Press down on dough with broad side of spatula until dough sticks together, adding up to 1 tablespoon of remaining ice water if dough does not come together. Divide dough into two balls, one slightly larger than the other. Flatten each into 4-inch-wide disk. Dust lightly with flour, wrap separately in plastic, and refrigerate at least 30 minutes.

Remove dough from refrigerator; let stand at room temperature to soften slightly, about 10 minutes.

Meanwhile, in a large bowl combine rhubarb, strawberries, sugar, corn starch, lemon juice, and cinnamon. Let stand for 15 minutes. Dot top with butter.

Before starting the lattice top, roll out half of your pie dough and line your pie dish with it. The dough should extend beyond the rim of the pie dish by about half an inch. Fill your pie shell with the fruit filling. Put it in the refrigerator to chill while you work on the lattice. On a lightly floured work surface, roll out the other half of your pie dough to the same extent as the first half (about 3 inches beyond the diameter of your pie dish). It's easier to work with the dough if it is chilled, so if the dough has softened too much, put the rolled-out piece on a flat cookie sheet and chill it in the refrigerator or freezer for a few minutes.

Cut the dough into even strips, 1/2-inch to 3/4-inch wide, depending on how thick you want your lattice strips. You can use a blunt knife, or a pizza wheel or a pastry wheel if you have one.

Preheat oven to 400º F.

Lay out 4 to 7 parallel strips of the pie dough, depending on how thick your strips are, on top of the filling, with about 1/2-inch to 3/4-inch space between them. Fold back every other strip. Place one long strip of dough perpendicular to the parallel strips. Unfold the folded strips over the perpendicular strip. Continue this process until the weave is complete over the top of the pie. Trim the edges of the strips flush with the dough of the underlying pie dish, which should be about half an inch over the sides. Fold back the rim of the shell over the edge of the lattice strips, and crimp to secure.

Brush lattice with beaten egg.

Place pie on baking sheet; bake until top crust is golden, 20 to 25 minutes. Reduce oven temperature to 350º F and continue to bake until juices bubble and crust is golden brown, 30 to 40 minutes longer.