In a large saucepan over medium heat, add the oil and bring to temperature. Add 1 tablespoon of the coriander seeds to the oil and toast, stirring constantly until they smell fragrant (a minute or so). Add the onion and garlic and fry for a few minutes until turning soft and translucent. Lower the heat to medium/low.
Add the spices, celery, carrot, sweet potato and turmeric and sweat alongside the onion for a minute, stirring constantly. Add the miso, bouillon and boiling water, stir well then bring to the boil. Allow to simmer for around 8 minutes.
While your soup is simmering, place a small dry frying pan over a medium heat and add your remaining 1 tablespoon coriander seeds. Toast until fragrant (around a minutand then transfer to a mortar and pestle or spice grinder. Very roughly grind and set aside.
Test a piece of carrot and a piece of sweet potato. They should be just soft enough to insert a fork easily. Turn off the heat and blend thoroughly with a stick blender until very smooth. If you’d like the soup thinner at this point, add some extra boiling water. If you’d like it thicker, return it to the hob and simmer for a little longer.
Spoon into soup bowls, top with a drizzle of your oat cream, a few coriander leaves and a sprinkle of toasted coriander seeds.