Wash the pollack fillet, pat dry, drizzle with lemon juice and season with sea salt and pepper. Wash the herb sprigs. Place the pollack fillet on a sufficiently large piece of baking paper, cover with the herb sprigs and seal the paper. Place on a baking sheet and bake in the preheated oven at 180 degrees (gas: 3, convection 160 degrees) for 20 to 30 minutes.
For the pea puree, peel and wash the potatoes. Peel the onion and garlic and dice everything. Heat the butter, add the potatoes, onions, garlic and peas, pour in the stock, bring to the boil and cook covered for 15 to 20 minutes.
Wash and roughly chop the parsley and marjoram.
Mix all ingredients for the mustard dip.
Coarsely mash the pea and potato mixture in the broth. Season with salt, pepper and nutmeg and sprinkle with the chopped herbs.
Serve the pollack with the pea puree and mustard dip, garnished with sprigs of herbs.