For crust, cut 2/3 cup Country Crock® Plant Butter into flour with pastry blender or two knives until coarse crumbs form. Stir in ice water, 1 Tbsp. at a time, until dough forms. Gently knead dough with floured hands and shape into two discs. Wrap in plastic wrap and refrigerate until chilled, about 30 minutes.
For filling, combine rhubarb, strawberries, sugar, tapioca, cinnamon and salt. Let stand 15 minutes.
Preheat oven to 4oo°. Unwrap dough and roll one disc on lightly floured surface from center to edges to form 12-in. circle. Press into 9-inch pie plate; trim edges of crust, reserve trimmings. Add trimmings to remaining disc and roll on lightly floured surface to form 14-inch circle; set aside. Cut into 14 1-inch strips.
Spoon filling into crust. Arrange 7 dough strips over filling, spacing evenly. Form lattice by placing remaining dough strip in opposite direction and weaving under and over strips. Trim edges of dough and crimp edges. Melt remaining 2 tablespoons Plant Butter and brush all over crust then sprinkle with sanding sugar.
Bake 15 minutes. Reduce oven temperature to 350°F and bake 50 minutes or until filling is bubbling and crust is golden brown. Remove from oven and cool on wire rack. Let cool at least one hour before serving.