Grease bottom and sides of a 15 x 10 x 1 inch jellyroll pan with vegetable oil; line with waxed paper, and grease lightly. Set aside.
Sift together flour,cocoa, and salt; beat egg yolks at high speed of an electric mixer 5 minutes or until thick. Gradually add sugar, beating well. Stir in lemon juice and set aside.
Beat egg whites (at room temperature) until stiff but not dry. Gently fold yolk mixture into whites. Gradually fold flour mixture into egg mixture. Spread batter evenly in prepared pan. Bake at 350º for 15 minutes.
Sift powdered sugar in a 15 x 10 inch rectangle on a linen towel. When cake is done, immediately loosen from sides of pan, and turn out on sugar. Peel off waxed paper. Starting at narrow end, roll up cake and towel together; cool on a wire rack, seam side down.
Unroll cake; remove towel. Spread cake with whipped cream and re-roll. Place on serving plate, seam side down; chill at least 1 hour.
Spread Creamy Mocha Frosting over cake roll. Garnish with candied cherries. Makes 10 to 12 servings.
Creamy Mocha Frosting:
1 Tbsp. instant coffee granules
1/3 cup boiling water
3 (1 oz) squares unsweetened chocolate
1/4 cup butter or margarine
Dash of salt
2 1/2 cups sifted powdered sugar
Combine coffee granules and boiling water, stirring until dissolved; set aside.
Combine chocolate, butter and salt in top of a double boiler. Cook over medium heat, stirring until smooth. Remove from heat; cool.
Stir in coffee mixture. Gradually add powdered sugar, beating on medium speed of electric mixer until smooth and creamy (about 1 minute). Use immediately. Yields enough for one cake roll.
Note: Yule log will slice neatly if stored in refrigerator.