Prepare a 9" square baking tin
Gently poach the rhubarb in the apple juice and sugar until it is just soft. Strain the juice into a jug and leave both rhubarb and juice to cool.
Put all the dry ingredients except the bicarbonate of soda into a bowl.
Take the liquid from the rhubarb and add enough soya milk to make it up to ½ pint.
Add the vinegar and the bicarbonate of soda and watch it froth!
Add this mixture and the oil to the dry ingredients and stir to a smooth consistency.
Fold in the rhubarb, pour into the greased, lined tin and bake in a moderate oven, gas mark 5, 190° C, 375° F for about an hour.
Turn out and cool, dust with icing sugar and serve.