Preheat oven to 220c/200c Fan/Gas 7.
Place diced pumpkin onto a baking tray and coat with Frylight before placing in the oven for 15 minutes.
Add diced onion, garlic, ground cumin, mustard powder, cayenne pepper and 100ml vegetable stock to a pan covered with a lid. Over a medium heat allow to simmer for 10 minutes or until the onion is softened.
Add the roasted pumpkin and the rest of the vegetable stock. Allow to simmer covered for a further 15 minutes until the pumpkin is completley soft.
Allow the soup to cool for 5 minutes and then place in to a food processor or use a hand blender. Blend until smooth and then place back into the pan.
Over a very low heat stir in the yoghurt, simmer gently for a few minutes before serving.