Mushroom Julienne

Cut the mushrooms into matchsticks rather than slices, stacking a few flat pieces at a time and cutting them into 3mm strips.

The cut is not decorative. Strips keep some bite in a wet sauce where thin slices go limp, and it is the cut that gives the dish its name.

Heat the oven to 200C/400F.

Melt the butter in a wide frying pan over medium heat and add the onion strips.

Cook the onion for 6-8 minutes, until soft and translucent but with no colour on it.

Turn the heat up and add the mushrooms.

Cook for 8-10 minutes, stirring occasionally, until the water they release has boiled off and the pan is dry and sizzling again rather than simmering.

Wait for the dry pan. Sauce added while the mushrooms are still giving off water thins out, and it separates into a greyish puddle under the grill.

Season with the fine salt and the ground peppercorns and stir in the lemon juice.

Take the pan off the heat.

Stir in the warm bechamel and then the smetana, off the heat, until everything is coated in a sauce thick enough to hold its shape on a spoon.

Add the soured cream off the heat and do not return the pan to it. Boiled soured cream separates into curds and whey, and the sauce cannot be brought back afterwards.

Divide the mixture between four small ovenproof dishes or ramekins, filling them to within 1cm of the rim.

Scatter the grated cheese evenly over the top.

Bake at 200C/400F for 10-12 minutes, until the sauce is bubbling at the edges.

Slide the dishes under a hot grill for 2-3 minutes, until the cheese is browned in patches.

Rest them for 4 minutes before serving. Straight from the grill the sauce is molten and will burn the roof of your mouth.

Scatter with the parsley and serve on plates with a teaspoon each, with bread for the sauce.