Step 2

With the processor running, pour in water slowly until the dough just holds together when pinched. Do not process more than 30 seconds. Add more water a teaspoon at a time if needed.

Step 3

Turn the dough onto a work surface and gather into a ball. Divide in half, flatten each into a disk, wrap in plastic and refrigerate for at least 1 hour.

Step 4

Roll one dough disk on a lightly floured surface to a 12-inch circle. Fold in half, transfer to a 9-inch pie pan, unfold and press in. Trim to a 1/2-inch overhang. Refrigerate while preparing the filling.

Step 5

Roll the second disk to a 13-inch circle and cut into 3/4-inch strips for the lattice. Place strips on a lined baking sheet, cover with plastic wrap and refrigerate for 10 minutes.

Step 6

Heat the oven to 400°F with a foil-lined baking sheet on the lower rack. Mix the cornstarch, 5 1/4oz sugar and cinnamon together, and put the strawberries and rhubarb in a large bowl.

Step 7

Sprinkle 2 tablespoons of the sugar mixture over the bottom of the chilled pie shell. Add the remaining sugar mixture to the fruit and toss gently to combine.

Step 8

Pour the fruit filling into the pie shell. Sprinkle with 1 tsp lemon juice and dot with 2 tbsp butter.

Step 9

Weave the chilled lattice strips over the filling, starting from the center. Trim strips to a 1-inch overhang, then fold them under the bottom crust and crimp to seal. Brush the lattice with milk and sprinkle with sugar.

Step 10

Bake the pie on the rack above the baking sheet for 35 minutes. If the edges brown too fast, cover them with a foil ring, then bake for about 10 minutes more, until the crust is golden and the juices bubble.

Step 11

Cool on a wire rack for at least 3 hours before serving at room temperature with whipped cream or vanilla ice cream.