Place the olive oil, onion and pumpkin into a large bowl. Add ¾ teaspoon of salt and be generous with the black pepper. Mix everything and then place onto a baking tray covered with baking paper. Roast in the oven for 25 minutes until everything is cooked and caramelized. Take out of the oven and place to the side.
Step 5: Add the vegetable stock to a large pan, together with the harissa, saffron threads, orange zest, ½ teaspoon of salt and a freshly ground pepper. Bring to a boil and add the roasted pumpkin and onions. Stir well and let the soup boil for 5 minutes at medium fire.
Step 6: Take the pan off the heat, add the crème fraiche and puree the soup. Serve with the roasted pumpkin seeds and coriander leaves on top.