To Prepare Crust:
In mixing bowl combine flour and salt; with pastry blender, or 2 knives used scissors-fashion, cut in margarine until mixture resembles coarse meal. Add yogurt and mix thoroughly to form dough; form dough into a ball, wrap in plastic wrap, and refrigerate for at least 1 hour (may be kept in refrigerator for up to 3 days).
Preheat oven to 400°F. Between 2 sheets of wax paper, roll dough to form a 10-inch circle, about 1/8 inch thick; carefully remove paper and fit dough into an 8-inch pie plate. Fold under any dough that extends beyond edge of plate and flute or crimp edge. Using a fork, prick bottom and sides of pie shell; bake until lightly browned, 15 to 20 minutes. Remove pie plate to wire rack and let cool. While crust is cooling, prepare filling.
To Prepare Filling:
In medium heatproof bowl sprinkle gelatin over boiling water and stir until dissolved; let cool slightly. Add cold water and whipped topping, stirring until completely blended. Cover and refrigerate until partially set, about 30 minutes.
In medium mixing bowl using an electric mixer on medium-high speed, beat egg whites until foamy; add cream of tartar and continue beating until stiff peaks form. Fold beaten whites into lemon gelatin mixture and pour into cooled pie crust; decoratively arrange kiwi slices over filling. Cover and refrigerate until set.
To Serve: Garnish with lemon slice.