Trim the leeks, remove the outer leaves and cut them into 3cm lengths. Wash well, but keep them intact. Mix together the mustard, miso, rice vinegar, mirin and honey. Season with pepper but be careful with the salt (the mustard and the miso makes the dressing salty anyway).

Steam the leeks in a steamer until they are tender to the point of a knife (but not collapsing), about 12-15 mins. Remove from the steamer and blot the leeks with a clean tea towel to remove excess moisture. Leave them to cool. Boil the eggs for about 7 mins, run under cold water and leave to cool.

Cook the sushi rice according to pack instructions. Peel the eggs and slice each in half. Tip the leeks into a large bowl and toss them in the dressing.

Divide the rice between four bowls, each topped with the dressed leeks. Add two egg halves on top, then a spoonful of the keta. Serve immediately.