Place tofu on a plate lined with paper towel. Cover with more paper towel and press down gently to absorb as much liquid as you can. Cut into cubes.

Heat half the oil in a medium saucepan over medium heat. Add ginger and the white parts of the spring onion (reserve greens for serving), cook for 1 minute until fragrant. Add stock and whisk to combine.

Add mushrooms and tofu and simmer for 2 minutes until mushrooms are cooked. Add bok choy and cook for 1 minute until wilted. Remove from heat and stir through miso.

Meanwhile, cook noodles according to packet instructions. Drain and divide between serving bowls and ladle in soup. Top with reserved spring onion, drizzle with remaining sesame oil and sprinkle over chilli flakes.