Dilute the jam in 1 cup water.
Add the flour to it in lots. Then add the oil and baking soda. Optionally you can add sugar because it's not very sweet otherwise. Stir well until homogeneous and add the raisins at the end.
Pour the mixture into an oiled and floured cake form. Bake at 329°F (165 °C) on the lower element only at first, then turn on the upper one too.
After you take it out of the form, sprinkle with powdered sugar.