Set a rack in the center of the oven and preheat to 350 F. Butter and flour a 9-inch springform pan.
Place the chopped fresh and dried fruit in a bowl. Stir the baking soda into the water until it is fizzy then pour over the fruit. Let sit while you prepare the cake, but no longer.
In a medium bowl, sift together the flours, baking powder, salt and spices. Separately, whisk together the oil, molasses, yogurt, eggs and brown sugar. Make a well in the center of the flour mixture and add the oil mixture, stirring to combine. Stir in the soaked fruit and the crystallized ginger, just until combined. Spoon the batter into the prepared pan and spread evenly. Cover the top evenly with the pumpkin seeds, sugar, sea salt and dot with the butter.
Bake for about 50 to 55 minutes or until the cake bounces back when pressed gently with your finger or a toothpick inserted in the center comes out clean.
Cool and serve. Makes 12 generous slices.