Simon Hopkinson revels in the obsessive purity and freshness of Japanese cooking; This meltingly sweet soybean coating, sticky and almost fermented, so deeply fine and almost pungent, transforms the slippery flakes to look like pieces of mother-of-pearl
During a recent lunch at the sushi bar of the fabulously chic Nobu, in the Metropolitan Hotel in London's Park Lane, I recalled a serving of aubergine that had quite knocked me sideways at another Japanese counter - in the same manor but in another era.

The time was around 1980; the place Ikeda in Brook Street. A chef friend and I used to meet here of a Sunday evening when we were young, keen and hungry.

Our plan was always the same: no menu, just a nod and "feed us please". We would sit at the counter to watch the chefs, deft with their honed knives, pleased to be left alone to cook up a storm. It was thrilling to watch and even more thrilling to eat.

We once watched chef Ikeda patiently pick away at steamed salmon frames after a busy lunch service. When some lauded chefs are chucking out unsightly lumps of trimmed salmon fillet, Ikeda is slipping off tasty whiskers from forgotten fish bones. Lessons to be learnt here.

I recently met Mark Edwards, the English chef of Nobu, after a spectacular lunch. It had been a lengthy meal, mainly because Edwards had been having trouble with a recent batch of black cod, used for making Nobu's celebrated black cod with miso. It had, apparently, not been behaving properly, sort of "falling apart". I sympathised. Cooking is hell when food fails to behave as you wish.

This wondrous black cod dish has to be one of the most important I have tasted in the past 10 years. The quality clearly owes something to the texture of this particular cod, imported from Japan, but also has much to do with the way the miso acts upon its flesh. This meltingly sweet soybean coating, sticky and almost fermented, so deeply fine and almost pungent, transforms the slippery flakes to look like pieces of mother- of-pearl.

The recipe is a Nobu secret, but don't feel too frustrated about that. As I mentioned, it was the memory of an aubergine dish that prompted me to write. It was one of the earliest impromptu courses that we enjoyed at the bar at Ikeda all those years ago. That sticky miso coating on the aubergine is so very similar to that of the black cod, that I guessed it had to have some sort of culinary lineage.

Nasu Dengaku (grilled aubergine with miso), serves 4

The white miso paste can be found in health food shops, as can the mirin, sometimes, and dashi soup stock. Of course, if you have a Japanese store near you, you have it made.

2 large aubergines, salt

For the miso paste topping:

200g white miso

2 tbsp sake (or dry sherry will do)

2 tbsp mirin

2 tbsp caster sugar

1 large egg yolk

6-7 tbsp dashi

1 x 5cm piece of fresh ginger, unpeeled

peanut oil

1 dsp sesame seeds

Halve the aubergines lengthways, cutting precisely through the stalk, which looks good left intact. With a small, sharp knife, cut into the flesh in a criss-cross pattern, fairly deeply, and sprinkle lightly with salt. Turn on to a cake rack, cut side down, leave to rest for 30 minutes or so, to allow any bitter juices to drip out.

To make the topping, put the first five ingredients into a double boiler and whisk together. Gently cook, stirring all the time with a wooden spoon, until visibly thickened. Now stir in the dashi little by little, until the consistency is that of double cream. Remove from the heat and plunge the pan into a bowl of iced water to stop the cooking. Grate the ginger and put into a small tea towel. Squeeze the juice into the miso mixture and stir in. Leave to cool completely.

Squeeze any excess juices from the aubergine and pat dry. Pour some peanut oil into a large frying pan to a depth of about 1cm. Heat until very hot and cook the aubergines, cut side down, until the surfaces are an even golden colour, then turn. Cook for a further 2 or 3 minutes, then tip out any excess oil. Turn the heat down to very low, cover and stew for a further 5-7 minutes or until aubergines are tender.

Pre-heat the grill. Spread about a teaspoon of the miso mixture over each aubergine half, covering evenly. (Note: it is difficult to make small quantities of this mixture, but it will keep in the fridge in a screw- top jar for a few weeks - or freeze it.) Sprinkle the aubergines with sesame seeds and place under the grill for a few moments to burnish the miso and to toast the sesame seeds. Serve at once with pieces of lemon for squeezing.

The Japanese obsession with food, its purity, its rigorous association with season, the formality, the freshness, the glee and greed displayed, is unlike almost any other culture's eating kick. I mean, not many other countries' cinematic outings can quite brilliantly revolve around the make or break of a simple noodle bar, and present it so beguilingly as the film Tampopo.

When I was asked by my friend and Bibendum confederate, Terence Conran, to contribute towards the new Conran Cookbook (published in 1980 as The Cook Book; republished last year, Conran Octopus, pounds 30), I jumped at the chance. Caroline Conran re-edited most of the recipes, and I introduced 50 or so new ones, mostly with an Asian theme.

I included a charming Japanese savoury custard called Chawan Mushi. It is steamed in an individual porcelain pot, to a trembling consistency, which breaks down into curds and broth as you spoon your way through it.

Chawan Mushi (Japanese egg custard with chicken and asparagus), serves 4

75g chicken breast, cut into small dice

2 tbsp light soy sauce

1 tbsp sake (or dry sherry)

2 large cloves garlic, peeled

4 medium eggs

700ml dashi, light chicken broth, or consomme

salt and a little cayenne pepper

1 tbsp mirin

8 freshly cooked, large asparagus tips, thinly sliced

16 perfect leaves of very fresh and green watercress

Marinate the chicken in the soy sauce and sake for 30 minutes. Cover garlic cloves with water in a small pan and bring to the boil. Drain and re-cover with salted water. Cook gently until soft. Drain and slice.

Process the eggs, broth, seasoning and mirin in a blender for 10 seconds. Pass through a fine sieve into a bowl and leave to settle for 10 minutes. Remove any froth with kitchen paper, laid on top.

Remove the chicken and carefully stir the marinade into the egg mixture. Lightly grease four ramekins with flavourless oil, then divide the chicken, asparagus and garlic between them. Carefully ladle the custard over and float four leaves of watercress on each. Cover loosely with circles of foil and steam gently for 20 minutes. The surfaces should be gently trembling. Remove from the steamer, with foil intact; leave to cool for 5 minutes. Remove foil and eat with teaspoons