Preheat oven to 350°.
Coat a 15 x 10-inch jelly-roll pan with cooking spray; line bottom with wax paper. Coat wax paper with cooking spray; dust with 2 teaspoons flour.
Beat egg whites at high speed of a mixer until foamy. Gradually add 1/2 cup granulated sugar, 1 tablespoon at a time, beating until stiff peaks form.
Beat egg yolks in a large bowl at high speed of a mixer for 4 minutes. Gradually add 1/4 cup granulated sugar, beating until thick and pale (about 2 minutes). Beat in lemon rind, juice, and oil. Gently fold egg white mixture into egg yolk mixture. Combine 2/3 cup flour, poppy seeds, baking powder, and salt, stirring well with a whisk; gently fold into egg mixture.
Spoon cake batter into prepared pan. Bake at 350° for 10 minutes or until cake springs back when touched lightly in center. Loosen cake from sides of pan, and turn out onto a dishtowel dusted with 1 tablespoon powdered sugar; carefully peel off wax paper. Sprinkle with 1 tablespoon powdered sugar; cool 1 minute. Starting at narrow end, roll up cake and towel together. Place, seam side down, on a wire rack; cool completely (about 1 hour).
Unroll the cake carefully, removing the towel. Combine the whipped topping and lemon curd. Spread the whipped topping mixture over the cake, leaving a 1/2-inch margin around the outside edges. Reroll cake, and place, seam side down, on a platter. Cover and chill for 4 hours. Sift 1 tablespoon powdered sugar over cake, and cut into slices.