Grease a small bowl that has a bit of a lip. Cut a piece of parchment paper the size of the bottom of the bowl. Spray the bowl and then place the parchment paper in the bottom. Spray again. Set aside.
In a medium bowl, mix together butter and sugar.
In a small bowl, sprinkle grated potato with baking soda. Set aside.
Add carrots, potatoes, currants and raisins to the butter and sugar. Mix together.
Add the flour, cloves, nutmeg and cinnamon. Mix only till combined.
Turn into prepared bowl. Cover with parchment lined foil and secure with kitchen twine to seal.
Using a pot with a pasta insert, or a pot with a trivet at the bottom, pour in just enough to the bottom that it will not touch the pudding bowl.
Bring water to a boil, then place the pudding in carefully. Steam for 3 hours.
Note: You will need to add boiling water to the bottom of the pot during this time as the water evaporates, so watch closely.