Wash the fish fillets, dry and lightly slice the skin, then salt. Heat butter and olive oil in a pan and fry the fillets completely. Reduce heat and cook on scrub for 3-4 minutes. On average, it should still be a little glassy. The cooking time depends on the thickness of the fillet. In the preparation add 1 sprig of rosemary and light yellow stems in the middle of the celery.
Ingredients for Beurre Blanc:
Peel and halve the shallots. Cut the butter into small pieces or cubes and cool. Put the vegetable broth, wine (Pinot Gris, dry Riesling or Riesling Spätles to taste), shallots and bay leaf in a frying pan and reduce the liquid by a third. Then add the cream and reduce the heat vigorously. The sauce should hardly simmer. Gradually add the butter pieces. Stir constantly with a whisk so that the butter mixes well with the liquid and the sauce becomes a nice cream.
If the sauce is still too liquid after adding butter, simply mix in the flour butter. Knead with room warmer or the same amount of flour. Gradually stir in the flour until you reach the desired consistency. Finally, season with a little lime cream and salt.
Ingredients for mashed potatoes:
Peel the potatoes and boil in salted water. Drain the water and mash the potatoes into a thick mash. Add a little hot broth, salt and nutmeg. You can also boil the potatoes in the broth immediately. Then leave the broth while draining, mash the potatoes and add the broth until you reach the desired consistency.
Put mashed potatoes on a plate and store the fillets. Pour the sauce on top. Garnish with celery and rosemary.