Preheat oven to 400F Combine flour and sugar. Cut in cubed butter with a pastry blender until mixture resembles coarse crumbs. Stir in the oil with a fork until all ingredients are moistened.
Stir in water, 1 tablespoon at a time, until dough leaves side of bowl and forms a ball. Roll out dough on a lightly floured surface to make a 14-inch circle.
Fit dough into an 11-inch tart pan with a removable bottom, pressing dough against the side of the pan without stretching the dough; trim excess dough. Prick the bottom of the crust with a fork.
Line crust with foil or parchment; fill with baking beans. Bake on the lowest rack of the oven for 15 minutes.
Remove foil and beans. Return to oven and bake 8 to 10 minutes more, until crust is golden. Set aside to cool.
Filling:
Soften gelatin in water for 5 minutes.
Combine rhubarb, sugar and orange peel in a 2-quart saucepan; cook, stirring occasionally, until rhubarb softens (8 to 10 minutes).
Stir in gelatin until dissolved. Stir in orange liqueur. Refrigerate mixture for 30 to 45 minutes.
Pour mixture into shell. Arrange sliced strawberries attractively on top of the rhubarb. Refrigerate 5 hours or overnight.