Preheat the oven to 350°F. Spray the bottom-only of a 5x9-inch loaf pan with nonstick spray.
In a large mixing bowl, whisk together the flour, salt, baking powder and baking soda.
In another bowl, whisk together the sugar, water, orange juice, oil, egg and orange zest; mix well to combine. Stir in the dry ingredients just until moistened. Fold in the cranberries (and nuts, if using). Spoon the batter into the prepared loaf pan.
Bake for 50 to 60 minutes or until a wooden pick inserted into the center comes out clean. Cool in the pan for 10 minutes. Remove to a wire rack to cool completely. Store, tightly wrapped or in a sealed container, in the refrigerator.
Notes
Greasing the bottom of the pan only and not the sides helps to avoid the bread from falling in the center.
Nutritional information does not include the optional walnuts.