Carrot Coriander Soup

This was deeemed new favorite soup by both members of the household, a particular victory for the girl who presently wishes to subsist on smoothies and crackers. Apologies for the metric. My source is on this side of the pond and, though I haven't yet taken to weighing everything with a scale, I've learned to eyeball a kilo of carrots here and there.

• 1 tbsp vegetable oil
• 1 onion , chopped
• 1 tsp ground coriander
• 1 potato , chopped
• 450g carrots , peeled and chopped (about 3-4 large carrots)
• 1 litre vegetable or chicken stock
• handful coriander (about ½ a supermarket packet) 

1. Heat the oil in a large pan, add the onion, then fry for 5 mins until softened. Stir in the ground coriander and potato, then cook for 1 min. Add the carrots and stock, bring to the boil, then reduce the heat. Cover and cook for 20 mins until the carrots are tender.
2. Tip into food processor with the coriander. then blitz until smooth (you may need to do this in two batches). Return to pan, taste, add salt if necessary, then reheat to serve.  Serves 4.