Heat oven to 375°F. Place pie crust in 9-inch glass pie plate as directed on box for One-Crust Filled Pie (do not trim or flute crust).
In medium bowl, mix 1 cup sugar, 3 tablespoons flour and the orange peel. Stir in eggs and sour cream. Add rhubarb; toss gently. Spoon into crust-lined pie plate. Fold edges of crust over filling, ruffling decoratively.
In small bowl, mix topping ingredients until crumbly. Sprinkle over filling.
Bake 50 to 60 minutes or until crust is light golden brown. Cool 3 hours before serving. Cover and refrigerate any remaining tart.