Preheat oven to 350◦. Thoroughly grease a 9 x 5-inch loaf pan.
Mix flour, salt, baking powder, baking soda, and sugar in a large bowl.
Grate zest from orange and place in liquid measuring cup. Juice orange and place juice in same measuring cup. Add vegetable shortening to measuring cup, then add enough boiling water to make a total of ¾ cup in the measuring cup. Stir until shortening is melted. Let cool at least 15 minutes.
Add orange mixture and egg to flour mixture, stirring just until mixed. Gently stir in cranberries and nuts.
Pour into prepared loaf pan and bake until a toothpick inserted in the center comes out clean, about 50-60 minutes.
Let cool 5 minutes, loosen edges, then carefully remove from pan and place on rack to fully cool.