Add a teaspoon of butter to the baking dish you're using for the persimmon pudding and use a paper towel to rub the butter over all the surfaces inside the mold. If it's a particularly intricate mold, take care to butter it well. Set aside.
PERSIMMON PUREE:
Cut away the stems from the persimmon and peel the skin with a vegetable peeler. Cut the persimmon into chunks and add them to a mini food processor. Pulse several times until the persimmon has been well pureed. Set aside.
TOAST THE WALNUTS:
Preheat the oven to 375°. Place the walnuts on a baking sheet and toast for 8-10 minutes, stirring occasionally until browned and fragrant. Roughly chop the nuts and set aside.
Turn the oven temperature down to 325° F.
ASSEMBLE THE PUDDING:
In a small mixing bowl, combine the flour, baking soda, salt and cinnamon. Whisk to blend.
Add the chopped walnuts and raisins and mix well. Set aside.
Use a hand mixer to beat the egg on high for 2-3 minutes or until light and fluffy. Gradually add in the sugar and continue to beat together until the mixture is thick, creamy and very well blended.
Stir in the persimmon pulp, grated carrot, melted butter and lemon zest. Stir well to combine. Add the buttermilk and stir to blend.
Add the flour mixture to the wet ingredients and stir until combined.
BAKE THE PERSIMMON PUDDING:
Pour the batter into the mold and set the dish inside a larger baking pan. Add very hot tap water to the pan so that it comes about halfway up the sides of the pudding.
Transfer to the oven and bake for one hour. (If you're using a glass bowl (like Pyrex) add an additional 10-15 minutes to the baking time.
After baking remove the pudding from the water bath and cool for 15 minutes on a wire rack.
FOR OPTIONAL LEMON CREAM:
In a small non-reactive pan, whisk the sugar cornstarch and salt to blend and gradually add the water and lemon juice while continuing to whisk.
Heat over medium heat and whisk constantly until the mixture thickens and becomes clear, about 3-5 minutes.
Remove from the heat and stir in the lemon zest. Lemon cream can be served warm or at at room temperature and can be stored for up to one week in the refrigerator.
TO SERVE PERSIMMON PUDDING:
Place a plate or cake stand (preferably one with a slight lip) over the pudding. Invert the pudding dish onto the plate. Serve warm with ice cream, whipped cream or lemon cream.
Notes
When reheating leftovers, give it a quick 20-30 seconds in the microwave for the best flavor.