In a large mixing bowl, stir together the flour, rolled oats, brown sugar, lemon peel, and baking soda. Stir in the melted butter or margarine and mix thoroughly.
For topping, reserve 1 cup of the oat mixture. Set aside.
For crust, press the remaining oat mixture into the bottom of an ungreased 13x9x2-inch baking pan. Bake in a 350 degree F oven for 20 minutes.
Carefully spread the cranberry sauce evenly over the partially baked crust. Stir the pecans or walnuts into the reserved topping. Sprinkle over cranberry sauce. Lightly pat topping into sauce. Bake in a 350 degree F oven for 25 to 30 minutes more or until top is lightly browned. Cool in pan on a wire rack. Cut into bars. Makes 24 bars.