Peel the sweet potato and chop into big chunks. Place in a pan of water, bring to the boil and cook for 15 minutes. Meanwhile, melt the butter gently in a saucepan, add the tahini and honey then allow to cool.
Place the walnuts in a loaf tin and cook in the preheated oven for 10 minutes. Sift the flour into a mixing bowl along with the baking powder and bicarbonate of soda. Add in the sugar and cherries then roughly crush the cooled walnuts into the mix.
Purée the potato then add the spices and orange rind. Add a few drops of vanilla extract to the melted butter mix then add to the purée, add the eggs.
Pour the purée into the dry mixture and then fold together just until mixed, not too much, you don't want a bricky bread! Pour into the loaf tin and bake for 50 minutes to 1 hour until a knife comes out clean.