I have this cooking on the stove right now. It has become a real favourite with us and is cheap to make and filling. Kumara are a native sweet potato to New Zealand - if you're unable to find that any other sweet potato or pumpkin could be substituted, although the flavour may not be the same. Do not let the curry powder overpower the flavours in the soup. This is a yellow curry powder, the type our mothers would have used when we were children.