1 tbsp(s), quick-cooking or minute variety
Fresh lemon juice
Uncooked rolled oats
¼ cup(s), do not use quick-cooking
Soybean cottonseed shortening
2 tbsp(s), solid vegetable variety
1 tsp(s), divided
1½ cup(s), cold
- Divide the oven in half with the rack; preheat the oven to 375°F.
- Mix the blackberries, 1/4 cup sugar, tapioca, lemon juice, vanilla, and cinnamon in a large bowl; set aside while you make the crust.
- Place 1/2 cup flour, oats, salt, and the remaining 1 teaspoon sugar in a food processor or a mini food processor; pulse until the oats are finely ground.
- Add the shortening and butter; pulse until the texture of coarse meal. Add the water and pulse just until the mixture gathers into a ball.
- Dot your work surface with water, then lay a piece of wax paper on it (the water will hold the wax paper in place). Sprinkle 1/2 teaspoon flour over the wax paper. Gather the dough together, place it on the wax paper, and pat it into a flattened circle. Sprinkle the remaining 1/2 teaspoon flour over the dough and top with a second piece of wax paper. Roll the dough to an 8-inch square. Peel off the top layer of wax paper.
- Pour the blackberry mixture into an 8-inch square baking pan. Lift up the dough with the bottom piece of wax paper, set it upside down over the filling, and peel off what was the bottom layer of wax paper. Tuck in the edges of the crust, pushing them down into the filling (as opposed to lifting them over the edges of the pan).
- Bake for 30 minutes, then crack the crust with a knife into 6 or 7 uneven sections. Press these down slightly into the filling. Continue baking until the berry mixture is bubbling through the cracks, about 5 minutes.