Preheat oven to 350°F. Line an 8- x 8-inch pan with Gefen Parchment Paper.
In a small pot, heat the oil, agave, and vanilla and stir to incorporate.
In a separate bowl, mix together the dry ingredients. Pour in the heated wet ingredients, dissolved kuzu, and ume (if using), and whisk until it forms a smooth, thick batter.
Pour half the batter into the prepared pan. Bake at 350°F for 15 minutes. Remove from oven and smear the top of the cake with apricot jam. Pour the rest of the batter on top and bake for 25 to 30 minutes until the top is browned. Remove from oven and allow to cool.
Serve warm or at room temperature.
If you’re making this cake in advance, it’s best to freeze it until you are ready to serve. To freeze, allow the cake to cool and remain at room temperature for 24 hours, then wrap well and transfer to the freezer. Defrost and reheat before serving.