Mixed Berry Streusel Pie

"Why this recipe works:Fresh berries guarantee a pie with great flavor, but their juices can make for a sodden crust and streusel. We wanted a pie that avoided this pitfall and featured intense berry flavor, that would slice neatly and that would have a crisp crust and crunchy streusel topping. A hybrid dough made by replacing some of the flour in our No-Fear Pie Crust recipe with graham cracker crumbs resulted in rich graham flavor and sufficient sturdiness. For intense berry flavor without too much liquid, we cooked a portion of the berries with sugar and lemon zest in a saucepan until syrupy. (A spatula dragged through the mixture should leave a trail when it’s thick enough.) To further tighten the filling, we tossed the cooked berry mixture with the remaining fresh berries and tapioca, which tasters appreciated for its ability to thicken without calling attention to itself. The raw pie dough formed the base of the streusel topping—simply fortifying the dough with oats for texture and brown sugar for sweetness before sprinkling the streusel on top made it an ideal component of our pie...."