For the lemon vinegar, add the lemon juice and zest to a measuring jug and add the same amount of white wine vinegar. Pour into a bottle, shake it up and leave in the fridge for at least 1 month to mature

Once the vinegar is ready, pass through muslin to remove the zest and pour into a clean bottle

Once ready to cook, slice the halibut fillet finely using a very sharp knife. Spread the strips out onto a plate and sprinkle over some lemon vinegar. Leave for approximately 20 minutes - the fish will start to 'cook' in the acid

Meanwhile, cook and refresh some green or wild asparagus in salted boiling water until tender but still firm

Peel the lemon and julienne the peel into very thin strips. Blanch the peel 4 times, replacing the water each time, until soft. Segment the flesh of the lemon, then cut the segments into little triangles. Set aside until ready to serve

For the dressing, add 4 tablespoons of lemon vinegar and the vegetable oil to a bottle. Season with salt and sugar to achieve a nice balance of sweet and sour, then shake thoroughly to emulsify

Drain off any juices from the halibut and arrange neatly onto plates. Season with a little salt, place a few lemon triangles on top of the fish and add a little lemon zest

Place the white and green asparagus and chervil in a bowl and dress with the lemon dressing. Season to taste

Arrange the asparagus and chervil neatly on top of the fish, then pour over a little of the dressing. Serve immediately