No-Faff Zucchini and Potato Soup

A re-post from the Veggies forum ... hope you like it!

2 tablespoons oil or butter
1 teaspoon ground coriander
1/2 teaspoon ground turmeric
1 onion, or about 4 spring onion bulbs, chopped
3 medium-sized zucchinis, cut into small pieces
500 g potatoes, washed, peeled and cut into small cubes
3 cups (750 ml) chicken or vegetable stock
2 tablespoons well-chopped coriander or parsley
2 tablespoons sour cream or thick plain yoghurt
Salt and pepper

Heat the oil or butter in a good, soup-sized saucepan to medium-high.
Throw in your ground coriander and turmeric and stir like hell for 1 minute.
Reduce heat to medium, chuck in the onions and stir them around for 3–4 minutes until they look pretty cooked.
Put in the chopped zucchini and potato and stir again for another couple of minutes, until the vegies are coated with all the other stuff.
Pour in your stock. Bring to the boil, then simmer, lid off, for about 10 minutes, or until the vegies are cooked.
Whiz the soup in a blender until it’s smooth.
Chuck it back on the stove, stir in sour cream or yoghurt, followed by your chopped herbs and seasonings.
Reheat over a low heat until hot enough to eat. Top with a dollop of extra sour cream or yoghurt if you like.