Grease bottom and sides of a 15x 10x 1-inch jellyroll pan with vegetable oil; line with wax paper, and grease wax paper with oil. Set pan aside. Beat egg yolks in a large bowl at high speed of an electric mixer until thick and lemon colored; stir in vanilla, and set aside. Beat egg whites until foamy; add cream of tartar and salt, beating until stiff but not dry. Fold in 3/4 cup powdered sugar. Fold whites into yolk mixture. Gradually fold flour into egg mixture. Spread batter evenly into prepared pan. Bake at 350 degrees for 10 to 12 minutes. Sift 1 to 2 tablespoon powdered sugar in a 15x 10-inch rectangle on a cloth towel. When cake is done, immediately loosen from sides of pan, and turn out onto sugared towel. Peel off wax paper. Starting at narrow end, roll up cake and towel together; let cool completely on a wire rack, seam side down. Combine sliced strawberries and 2 tablespoons sugar; set aside. Beat whipping cream until foamy; gradually add 3 tablespoons sugar, beating until soft peaks form. Unroll cake. Spread cake with sliced strawberries and half of whipped cream; reroll cake, without towel. Place on serving plate, seam side down; spread remaining whipped cream on all sides. Garnish with whole strawberries, if servings. ----