Position the oven rack in the center of the oven. Preheat the oven to 325°F. Spray the mini bundt cake tins with nonstick spray.
Grate ginger into a large bowl. Stir in the molasses, sugar, and oil. Mix well. In a medium bowl, sift together the flour, cinnamon, cloves and black pepper.
Bring the water to the boil in a saucepan, stir in the baking soda, and then mix the hot water into the ginger-molasses mixture.
Gradually whisk the dry ingredients into the batter. Add the eggs, and continue mixing until everything is thoroughly combined. Pour 3 tablespoons of batter into each cake cavity and bake for about 10-12 minutes, until the top of each cake springs back lightly when pressed or a toothpick inserted into the center comes out clean.
Cool the cakes for at least 10 minutes. Run a knife around the edge of the cakes to loosen them from the pans. Remove the cakes from the pans.