In a large saucepan, bring the water to a gentle simmer.

Add the dashi powder, soy sauce, mirin and sugar.

Simmer the broth gently for about 5 to 10 minutes.

Taste for seasoning. Add more salt or soy sauce if necessary, or you may need to dilute with more water if the broth is too strong or salty.

Fill a large saucepan with boiling water.

Bring the saucepan to the boil on high heat.

Add the noodles.

Use a pair of tongs or chopsticks to gently loosen and separate the noodles. This step should take just a few seconds.

Once the noodles have separated, drain the noodles immediately.

If the tofu pouches are frozen, defrost them at room temperature.

Slice off a small piece at one end so that you can open the pouch.

Gently open the pouch, taking care not to rip the tofu.

Carefully fill the pouch with udon noodles, leaving enough room to seal the pouches later.

Wash the spring onions (scallions), as they are easier to manoeuvre when they are wet.

Use one sprig of spring onion (scallion) to tie a double knot at the top of each pouch.

Bring the dashi broth to a gentle simmer.

Carefully place the stuffed tofu pouches in the broth.

Simmer gently for about 5 minutes, which should be enough time to warm through the tofu and the noodles inside.

Use a large slotted spoon to carefully remove a stuffed tofu pouch to a large bowl. Repeat with the remaining tofu pouches.

Ladle some dashi broth over each tofu pouch.

Serve immediately.