Spiced sweet potato soup

1 tbsp olive oil

1 onion, roughly chopped

1 leek

3 cm of ginger

2 tsp ground cumin

2 tsp sweet paprika

1 tsp ground coriander

1 tsp cinnamon

2 sweet potatoes

2 parsnips

2 carrots

1 veg stock dice

1 L of water

1 pinch salt

1 pinch pepper

150 g of Greek yoghurt

15 g mint leaves, chopped

10 g coriander leaves, chopped