Place cold water and kombu and bring it to boil.
When bubbles start to come up then take kombu out from pot and turn off the heat. (sobadashi)
Add bonito flakes into kombu dashi and leave two to five minutes.
Strain dashi and cool them down. (katso dashi)
In a sauce pot, add four dashi, 1 mirin and katsuo dashi.
Bring it to the boil and turn off.
Keep in the fridge. You can keep for four to five days in the fridge.
Mix all the ingredients into a bowl and mix well.
Heat nonstick pan well and pour egg mix onto the pan. Do not pour egg mix too much, make like a crepe.
Roll up egg sheet from bottom side then you see small egg roll (core) on top side.
Put some oil onto the pan and pour egg mix.
Roll egg from top side then you see egg roll on the bottom side and move egg roll to the top side. Repeat until all the egg mix gone.
Wrap in cling film and make a rectangle form.
Soak dried shiitake in the water and leave for one night.
Slice soaked shiitake and place into sauce pot.
Add dark soy sauce and honey.
Stew them until all the juice is reduced by half.
Keep in a jar. Keeps up to a month in the fridge.
Tie one side of soba noodle with a rubber band, and boil for six minutes.
Strain soba and wash in the cold water, drain and leave soba noodles on a tray for one hour.
Place sushi mat and put sushi nori sheet on the mat.
Cut off rubber band parts of soba and spread soba noodle onto nori sheet, leave space, 1.5cm top side of nori.
Cut egg roll into six batons and put egg roll on the centre.(horizon)
Put cucumber, chive and shiso leaf on egg roll. Keep the stuffing tight on the centre.
Grab bottom side of bamboo mat and nori together and roll. First roll, bottom edge part is going to be on top side of filling.
Second roll, keep rolling but taking bamboo mat off from bottom side.
When sushi has almost shaped, place sushi mat again and put sushi roll on bottom of mat and roll from bottom side. Shape it and leave 10 minutes.
Cut sushi roll into eight pieces and serve with soba dashi and garnish.