First make the base for the soup. Toast the cumin seeds and coriander seeds in a dry pan on a medium heat for a few minutes until fragrant. Peel the ginger and chop the woody part off of the lemongrass stalk. Chop everything into small chunks and place into a blender. Blend for 1 minute or until completely smooth.

Chop the tofu into 1 inch chunks and fry for 3-4 minutes on one side, then flip the pieces and cook for a further 4 minutes until golden brown. Take off the heat and set aside.

Chop the carrot, red onion and red pepper into strips that are roughly the same size. This will help them cook evenly. Heat a little oil in a large sauce pan and saute the vegetables with the blended base ingredients for 5 minutes stirring occasionally. Add the coconut milk and vegetable brother and bring to a simmer.

While the soup is simmering, place the rice noodles into a heatproof bowl and cover with just boiled water. Let sit for 10 minutes. After 10 minutes, drain.

Slice the mushrooms and fry in a small pan until golden brown. Then Slice the spring onion into thin slices.

Assemble the soup by first placing some rice noodles in the bottom of a dish, then topping with some of the soup mixture, some tofu, mushrooms and fresh spring onion. Sprinkle on a few sesame seeds if desired.