Combine the flour, sugar, salt, baking powder, and baking soda. Add the cranberries and walnuts, and stir to coat with flour. Mix together the egg, oil, orange juice, and orange zest. Pour the egg mixture into the flour mixture, and stir until just blended. Spoon the batter into the prepared pan.
Bake for 50 minutes in the preheated oven, or until a toothpick inserted near the center comes out clean. Cool in pan for 10 minutes, then remove to a wire rack, and cool completely.