Preheat oven to 250°F and butter or oil a steamed pudding mold (or a 6-cup glass, ceramic, or metal bowl).

In a blender or food processor, puree the persimmons, sugar, vanilla, and water.

Mix with the flour, salt, baking soda, raisins, and nuts.

Transfer batter to the prepared mold or bowl, and cover with a lid or plate. Place mold inside a deep, wide, oven-safe pot and fill the pot with water to about halfway up the mold.

Bring the pot of water, with covered mold inside, to a boil on the stovetop over high heat.

Cover pot and transfer to preheated oven. Bake until pudding is firm to the touch (2 t0 3 hours), and a toothpick inserted into the center comes out relatively clean—it doesn't need to be totally dry, but you don't want it too gooey either.

Unmold the steamed pudding onto a serving platter and drizzle with an optional lemon sauce.

Melt butter in a saucepan over low heat, stirring regularly to prevent burning.

Add lemon juice in a slow stream, whisking well.

Stir in sugar.

Before the sauce gets too hot, pour a little bit of it into a dish along with your beaten egg, stirring well. Add a little more sauce to the egg and stir well again. (This step warms the egg slowly, preventing it from poaching in the hot liquid and adding unwanted bits of cooked egg to your sauce.)

Return saucepan to the stovetop and add egg, stirring frequently until the sauce has thickened—about 10 to 20 minutes, depending on the width of your pan.