Hi Rosie, give it a go with regular sweet potato. I’ve never tried it in this recipe, but the flavours won’t be substantially different than kumara (red skinned sweet potato). Let me know how it turns out if you do try it.
Being British I haven’t heard of Alison Holst but your post means I will be using amazon to get one of her books as I love different cookery books. Will be interested to give this soup ago but have no chance of getting kumara over here – do you think sweet potato would work as a substitute?
Chez Moi 
Hi Rosie, give it a go with regular sweet potato. I’ve never tried it in this recipe, but the flavours won’t be substantially different than kumara (red skinned sweet potato). Let me know how it turns out if you do try it.
Being British I haven’t heard of Alison Holst but your post means I will be using amazon to get one of her books as I love different cookery books. Will be interested to give this soup ago but have no chance of getting kumara over here – do you think sweet potato would work as a substitute?