Trim the leeks, cut them into 8 cm / 3 in even sections, and wash them thoroughly to remove any soil.

Arrange the leek sections in the frying pan with 20 g / 0.7 oz butter, 10 g / 0.35 oz white miso paste, and 1 bay leaf.

Pour in about 350 ml / 1.5 cups water, enough to come halfway up the leeks, then cover the pan.

Bring the liquid to a gentle simmer over medium heat and cook the covered leeks for 10 to 12 minutes.

Test a leek section with the tip of a chef's knife; it is cooked when it slips off the knife easily.

Meanwhile, bring water to a simmer in the saucepan and gently lower in the 3 eggs.

Cook the eggs for 9 to 10 minutes, then transfer them immediately to a bowl of ice water to cool.

Peel the cooled eggs, then separate the yolks from the whites.

Mash the egg yolks with 1 tbsp Dijon mustard and a pinch of salt until completely smooth.

Gradually drizzle 100 ml / 3.4 fl oz neutral oil into the yolk mixture while whisking continuously to form a thick mayonnaise.

Finely chop the egg whites, then fold them into the mayonnaise.

Stir in 1 tbsp chopped gherkins, 1 tbsp chopped capers, 1 tbsp chopped dill, 1 tbsp chopped chervil, and 1 tbsp chopped tarragon.

Season the gribiche sauce with black pepper and additional salt to taste, then set it aside.

Remove the cooked leeks from the pan and discard the bay leaf.

Boil the remaining miso butter cooking liquid uncovered until it reduces to a glossy, syrupy glaze.

Spread the gribiche sauce generously across 4 serving plates, then place the warm leeks on top.

Spoon the reduced miso butter glaze over the leeks, then finish with dill sprigs and coarsely crushed roasted cashews.