Active Time

　　40 min

　　Total Time

　　6 hr (includes making dough and cooling pie)

　　Beneath a humble, oaty streusel topping lies a sleek, inky jumble of plums and blackberries—talk about a delicious contrast. A combination of cornstarch and tapioca in the filling helps to keep the colors of the fruit true and to set up their juices nicely without becoming too thick.

　　

Ingredients

8 servings

　　1 3/4 pound ripe plums, pitted and quartered

　　3/4 pound blackberries (2 cups)

　　1 1/2 cups sugar, divided

　　3 tablespoons quick-cooking tapioca

　　2 tablespoons cornstarch

　　1 teaspoon grated lemon zest

　　3/4 teaspoon salt, divided

　　1/2 recipe all-butter pastry dough

　　1 cup old-fashioned rolled oats

　　1/2 cup all-purpose flour

　　1 stick cold unsalted butter, cut into bits

　　Equipment: a 9 1/2-inch deep-dish pie plate

　　

Step 1

Put a foil-lined large baking sheet in lower third of oven and preheat oven to 375°F.

　　

Step 2

Toss plums and blackberries with 1 cup sugar, tapioca, cornstarch, zest, and 1/4 teaspoon salt in a large bowl.

　　

Step 3

Roll out dough into a 13-inch round on a lightly floured surface with a lightly floured rolling pin. Fit into pie plate. Trim excess dough, leaving a 1/2-inch overhang. Fold overhang under and press against rim of pie plate, then crimp decoratively. Chill while making streusel.

　　

Step 4

Stir together oats, flour, and remaining 1/2 cup sugar and 1/2 tsp salt. Blend in butter with your fingertips until mixture forms small clumps.

　　

Step 5

Mound filling in shell. Crumble streusel evenly over filling.

　　

Step 6

Bake pie until streusel is golden and filling is bubbling, 1 1/4 to 1 1/2 hours. Cool completely, 3 to 4 hours.