The day before you plan to serve, soak the dried kombu in the water and place in the fridge overnight to infuse.

The next day, remove the kombu and bring the water to the boil. Add the bonito, turn off the heat and then strain the dashi into a clean pan. Cover and set aside in the fridge while you make the udon.

To make the udon, combine the water and salt and mix until completely dissolved.

Place the flours into a large bowl, then hold your fingers down separately to imitate a few sets of chopsticks and mix the flour for a few minutes by swirling your ‘chopsticks’ around.

Gradually pour in around a quarter of the water as you mix the flour with your fingers.

Continue to add the water as you mix, making sure the flour is mixed throughout and maintains a damp sandy texture rather than a lumpy dough.

Press together the dough and fold (without kneading) to form a ball, making sure you pick up any bits of dough that have stuck to the bowl as well. Place the dough in a large, sealable plastic bag.

Flatten the dough with your feet until it is large enough to stand on, then step back and forth, changing the angle from time to time, for 5 minutes.

Take the dough out of the bag, roll it up into a cylinder, then place it back in the bag and rest it in the fridge for 30 minutes.

Repeat the stepping, rolling and resting process twice more, then step on the dough one more time to flatten it into an oval shape.

Fold the edges of the dough into the centre, then continue to knead the dough in this way to eventually form a ball with a concentrated fold at the centre.

Step on the dough once more until it is about 1cm thick, then lightly flour a work surface and roll the dough a few times in each direction to even it out.

Wrap the dough around the rolling pin, then apply pressure to it to make it thinner, around 2-3mm.

Scatter more flour over the dough and fold the top third down and the bottom third up. Dust with more flour and cut the folded dough into 3mm ribbons.

Bring a large pan of water to the boil and cook the udon noodles for 10-15 minutes.

While the noodles cook, finish the dashi. Place the mirin in the microwave and cook for 1 minute to burn off the alcohol.

Mix the sugar into the mirin, then pour this mixture into the dashi along with the soy sauce and half the amount of salt. Gently bring the dashi to a simmer.

Once the noodles are cooked, drain and wash or rinse in cold water until completely cold.

Once the dashi is almost boiling, taste and see if you want to add the remaining salt.

To serve, divide the blanched noodles between 4 bowls and pour the hot dashi over the top. Scatter with the spring onions and serve.