Sweet potato and carrot soup

Ingredients:
1 onion - sliced
2 small sweet potatoes (skinned and cut into thick chunks)
1/2 carrot ( cut into thick chunks)
1/2 inch ginger - grated ) optional
chicken stock
1 tbsp butter and some olive oil

Method:
1. Heat oil and butter in a frying pan.
2. When butter has melted, saute onions till translucent and add sweet potatoes and carrots. You may add or omit ginger at this point. The ginger will give the soup a little kick.
3. Add 250 mls of chicken stock and boil then sweet potatoes and carrots are soft. Add salt to taste.
4. If stock boils down, add about another 100 mls of water.
5. When the veges are soft, remove from heat and put in a deep bowl and blitz. You can blend it finely or leave if chunky!
6. Add more soup if you prefer it thinner. Bring to boil again and it is ready to serve.