Sterilise 4 jars in the dishwasher or alternatively wash the jars with very hot soapy water. Then rinse them well and put them upside down on an oven rack, at the lowest temperature your oven goes for 15 minutes.
Clean and scrub the apples, potato and carrots and them all with the skin on.
In a large bowl add the potato starch, oat flour,, buckwheat flour, sorghum flour, baking soda, and spices.
Cream the butter and brown sugar for about 2 minutes until it is smooth, then briefly beat in the eggs. Add a little flour after each egg to prevent the mixture curdling.
With a wooden spoon, stir in the carrots, apples, potatoes and raisins.
Mix the dough well and spoon it into 4 sterilized, widemouth canning jars. Fill the jars just over ½ full (which is about 550g in each jar). There must be empty space between the top of the pudding and the top of the jar to allow for expansion of the pudding as it cooks.
Place the canning rack in the canner or pot and pour in about 16 cups of hot water that it will be no more than 3 inches up the sides of the jars. Bring the water to a boil just before filling the jars with the pudding.
Clean the sides of jars with a spatula above the pudding line and wipe clean the tops of the jars for a good contact with the lids. Screw on the tops.
Simmer the pudding in the jars for 2 hours with out removing the lid. If you think the water may run dry then definitely lift the lid and top it up a little. There must always be water in the bottom.
Serve the pudding with rum sauce or cream and enjoy !
The pudding will keep on the shelf at room temperature for at least 3 months if it is sealed.