Butter an 8-cup lidded pudding mold and set aside. In a small saucepan over low heat, combine brandy, raisins, and currants, and bring to a simmer. Remove from heat and let sit for 15 minutes. Meanwhile, in the bowl of an electric mixer, cream together butter and sugar. Beat in egg yolks, vanilla, and lemon juice. Cut tops off persimmons. Scoop out pulp and push through a strainer, discarding seeds and skins. Combine with half-and-half. Dissolve baking soda in hot water and add to egg mixture. Sift together flour, spices, and salt and add to persimmon mixture. Beat just until combined. Stir in pecans. In a clean bowl, beat egg whites until stiff peaks form; fold into batter. Pour into mold over raisins and currants; clamp on lid. Choose a pot large enough to hold the mold with a 2-inch clearance on all sides. Place a wire rack or folded dish towel in the bottom of pan and fill with enough water to reach halfway up sides of mold. Cover and bring to a boil, then turn down to a simmer. Place mold on rack in pot. Cover and steam pudding for 2 hours and 20 minutes. Add boiling water as necessary to maintain water level. Remove mold from pot and let cool, uncovered, for 15 minutes before serving.