If you’ve ever tried a native persimmon, you know that it’s full of seeds. From 8 persimmons I got 3/4 of a cup of pulp once I’d removed all of the seeds. With store-bought persimmons, you may need only two or three to get enough pulp.
Preheat oven to 350F. Oil a 8- or 9-inch baking dish or cake pan. (I used a round silicone cake pan.)
Remove the skin from the persimmons along with any seeds. Mash pulp and measure. Peel the apple and chop into 1/2-inch cubes.
Place the apple into a saucepan along with the 1/8 cup agave nectar, water, cinnamon, and ginger.
Cook over medium-low heat, stirring, until the apple softens, about 10 minutes. Add the persimmon and set aside.
In a large bowl, combine the flour, baking soda, salt, and cinnamon. In a large measuring cup or small bowl, mix together the water, orange juice, 1/2 cup agave nectar, cider vinegar, and vanilla. Make a well in the center of the dry ingredients and add the wet ones along with the soy yogurt or apple sauce. Stir until well-moistened. Fold in apple mixture.
Pour into the prepared pan. Bake for 30-40 minutes, until a toothpick inserted in the middle comes out clean. Cool in the pan for at least 15 minutes before removing from pan. Sprinkle with powdered sugar before serving, if desired.