Combine flour and sugar. Cut in butter with a pastry blender until mixture resembles coarse crumbs.
Stir in 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 bottom of the crust with a fork.
Line crust with an 18-inch piece of foil; fill to rim with dried beans. Bake on the lowest rack of a 400 F oven for 15 minutes.
Remove foil and beans. Return to oven and bake 8-10 minutes more, until crust is golden. Set aside to cool.
Combine rhubarb, sugar and orange peel in a 2-quart saucepan; cook, stirring occasionally, until rhubarb softens (8-10 minutes).
Soften gelatin in water for 5 minutes. Stir into hot rhubarb mixture until gelatin is dissolved.
Stir in orange liqueur.
Refrigerate mixture for 30-45 minutes.
Pour mixture into shell.
Arrange sliced strawberries attractively on top of the rhubarb. Refrigerate 5 hours or more.
To serve, remove rim from pan, leaving the tart on the bottom of the pan. Garnish with whipped cream and cut into wedges.