Heat oil in a large saucepan and saute the onion until soft.
Stir in the cumin, garlic, chilli and lemon zest and cook until fragrant.
Add the kumara and vegetable stock and season to taste. Bring to the boil, reduce the heat, cover and simmer for 20 - 30 minutes until kumara is tender.
Puree the soup and bring back to the boil, add the quinoa and extra water, reduce the heat, cover and simmer for 15 - 20 minutes until quinoa is cooked.
To make the garnish, heat the oil in a small frypan and saute the garlic until it starts to change colour. Add cumin and cook until it starts to bubble. Stir in the coriander and cook for a few seconds until it starts to wilt.
Stir the garnish and season to taste.
To serve, pour the garnish on top of each bowl of soup together with a good squeeze of lemon juice.