OPTIONAL STEP: If using whole coriander seeds, I recommend pre-roasting them on a dry pan until golden and fragrant and pounding them to a powder in a pestle and mortar.Place all the paste ingredients in a herb chopper or a food processor, add about 4 tbsp of water and process until you get a uniform paste.You can cook your vegetables in the soup (see STEP 7) or separately, like I did. It takes a bit more work but I find that they taste better than if you simply boil them. If you want to cook them separately, heat up the oven to 225° C / 435° F and line a tray with a piece of baking paper. Coat diced butternut squash in a tablespoon of oil, season with salt or tamari / soy sauce and bake for about 30 mins, until golden. Heat up one tablespoon of oil in a wok and stir fry broccoli florets for about 1 minute, add sliced beans and stir-fry for about 1 minute. Season with tamari or soy sauce.Cook noodles according to the instructions on the packet.Put the bowls into a warm oven (100 °C / 210 °F) to heat them up for serving.Heat up a tablespoon of oil in a medium size pot. Add Khao Soi paste to the hot oil and stir-fry it for about 4-6 minutes, until slightly darkened. Add vegetable broth and coconut milk and allow them to come to the boil. Season with vegan fish sauce (tamari or soy sauce), fresh lime juice and sugar to taste.If you want to cook your vegetables in the soup, place diced butternut squash in the soup, allow the soup to come to the boil and simmer for about 7 minutes, add broccoli florets and sliced beans and cook for a 5 further minutes. Pour over cooked noodles and serve with fresh coriander.