Trim any thick stalks and dry leaves away from the Brussels sprouts and roughly shred. Peel and crush or finely grate the garlic. Peel and grate the garlic. Halve the chilli, scraping out the membrane and seeds for less heat, and finely chop. Separate the coriander leaves and stalks (save the leaves for later in the recipe) and finely chop the stalks.
Drizzle 1 tbsp oil into a pan and bring to a medium heat. Slide in the chopped garlic, ginger, chilli and coriander stalks and fry for 1 min, stirring frequently.
Pour 800ml boiling water into the pan and scatter in the basmati rice. Swirl in 1 tbsp tamari. Return to the boil, then reduce the heat and simmer gently for 6 mins.
Once the broth has simmered for 6 mins, slide in the shredded sprouts and continue to simmer for a further 4 mins, till the rice is tender and the sprouts are softened but retaining a slight bite.
Have a taste of the broth and add more tamari if needed. Swirl in a pinch of ground pepper. Ladle the soup into bowls and scatter over the remaining coriander leaves.