Curried Parsnip, Carrot & Ginger Soup

I had a lot of parsnips left in my garden that needed to be used up, and my son absolutely loves soup, so i used them to make a big batch of soup.
He is only two but he loves food with a lot of flavour and he especially loves anything curried.
So i made up this recipe for him.

Makes 11 child portions
Prep time 20 minutes
Cook time 1 hour

2 tbsp olive oil
1 large onion cut into wedges
1 kg parsnips cored and cut into 3cm lengths
1 kg carrots sliced in half and cut into about 3
1 tbsp grated  fresh ginger or ground ginger
1 tbsp ground cumin
1 tbsp ground coriander
1 tbsp dried coriander
1 tsp brown sugar
½ tsp turmeric
Fresh ground pepper to season
2 tins of plummed tomatoes
1 ½ litres of vegetable stock

In a large roasting tin mix the first 11 ingredients and roast for 30 to 35 minutes.
Blend the vegetables till smooth with the tomatoes and vegetable stock, then heat through in a saucepan, season to taste and serve.