Combine flour, soda, salt, and spices in a large mixing bowl; mix well. Stir in raisins, apple, and currants.
Combine molasses, water, and suet; add to dry ingredients, mixing well. Spoon mixture into a well-greased 2 1/8-quart mold; cover tightly.
Place mold on rack in a large, deep kettle with enough boiling water to come halfway up mold. Cover kettle; steam pudding 3 hours in boiling water, replacing water as needed. Unmold and serve with Sherried Hard Sauce. Refrigerate leftover pudding.