Combine the tare ingredients in a small saucepan. Bring to a boil and then lower the heat, simmering steadily for 5 minutes. Strain and set aside until needed.
Heat the oil in a large pan over a medium heat, then add the mushrooms. Cook for 5-6 minutes until browned. Remove from the pan, set aside and cover until needed. Add the onion, salad onions, garlic and ginger to the pan and cook for 1-2 minutes until fragrant and just starting to brown. Add the dried mushrooms, kombu and 1 litre of water. Bring to the boil and then lower the heat. Cover and simmer for 25 minutes.
Marinade the tofu in 1½ tbsp of the tare for 20 minutes. Heat a griddle pan over a medium heat and then add the tofu, grilling for 1 minute on each side until you have nice dark griddle marks. Cover and keep warm. Drain the broth, discarding the vegetables except for the garlic. Squeeze the garlic cloves out into a mini blender and add a ladle of the broth. Blitz until completely smooth, then add back to the pot along with the broth. Stir together and keep warm over a low heat.
Cook the noodles according to the instructions on the packet. Ladle the remaining tare into four bowls, followed by the broth. Add the noodles and then arrange the browned mushrooms, grilled tofu, sliced spring onions and chilli on top. Scatter over the toasted sesame seeds and finish with a splash of sriracha.