Weigh the bones and cover with cold water. Refrigerate overnight to extract the blood from the bones and marrow. Discard the soaking water and then add twice the weight of the bones of fresh cold water. Measure the distance from the top of the water to the top of the pot.

Bring to a simmer, using a fine mesh to skim the grey scum rising to the surface of the water, stirring occasionally. Continue until the scum rising to the top is white rather than grey. This will take about 2 hours.

Cover the pot and boil for a further 6 hours (the water should be active and bubbling but the heat does not necessarily have to be high), topping up the water to the starting level and stirring every half hour. Remove the lid and reduce the liquid for about 4 hours until you reach the consistency you want. The more you reduce the liquid, the thicker and stronger the soup base will be.

Strain the soup and cool rapidly by stirring in a bath of iced water until it is room temperature. Cover and refrigerate overnight.

Make the tare, add the dried seafood, kombu and cold water to a non-reactive container and refrigerate overnight.

Transfer to a saucepan and heat over very low heat for about 1 hour until just warm to the touch. Remove the seafood and measure the volume of dashi produced. Add salt in the ratio of 1:5 and stir over heat until the salt is fully dissolved. Add the vinegar and set aside.

To make the bonito powder, blend dried bonito flakes to a fine powder. Combine all the ingredients in a saucepan and bring to a boil. Allow to cool and strain.

To assemble the ramen, follow the instructions in the video.