Peel the shallots. Clean and shine the mushrooms. Cut both into fine cubes. Wash lemon hot, grate dry and finely grate peel. Halve lemon and squeeze juice from one half. Use the rest for other purposes.
Wash parsley, shake dry and chop finely, except for a few leaves for garnishing.
Heat 1 tablespoon of butter in a frying pan. Fry the shallots and mushrooms until golden brown, turning them over. Pull the pan off the heat. Mix with breadcrumbs, chopped parsley, ketchup, lemon zest and juice.
Season to taste with salt and pepper.
Rinse plaice fillets cold, dab dry and cut in half lengthwise to form 8 strips. Place the strips next to each other and season with salt and pepper. Spread the mushroom mixture on top and press down lightly.
Roll up plaice fillets from the thin end. Tie together with roasting tape to form rolls. Place on a greased baking tray, spread 1 tbsp. butter in flakes on top and bake in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: s.
manufacturer) cook for about 20 minutes.
In the meantime, prepare peas in boiling salted water according to the instructions on the packet. Drain and toss with 1 teaspoon butter in a saucepan. Season to taste with salt, pepper and nutmeg. Arrange on plates with plaice rolls.
Garnish with parsley leaves.