North African Sweet Potato Soup

1 tbsp olive oil
1 large onion, chopped
2 garlic cloves, crushed
3 tspn cumin seeds, toasted & crushed
3 tspn coriander seeds, toasted & crushed
3 tspn freshly grated ginger
1 tspn cayenne
1 tspn turmeric
1 kg sweet potatoes, peeled & cut into chunks
6-8 cups vegetable stock
½ cup fresh orange juice
freshly ground salt & pepper
cr?me fraiche (or a mixture of fresh & sour cream)
coriander sprigs
Heat oil in a large pot and gently saute onion and garlic until softish. Then add cumin, coriander, ginger, cayenne and turmeric, continually stirring and briefly cook to toast. Add sweet potatoes and toss to coat well. Then add stock to cover, orange juice and seasonings. Mix well and cook for about 30 mins until tender, adding more stock if needed. When ready, blend the soup and ladle into individual bowls. Serve topped with a little cr?me fraiche and a garnish of coriander.