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    Home » Recipes » German Recipes

    Quick Flounder Fish Fillets In Creamy Mustard Sauce

    Published: Mar 11, 2022 by Angela Schofield · 1 Comment

    Jump to Recipe Print Recipe

    This quick oven baked flounder recipe stems from the Baltic Sea and is very popular in the North-East of Germany and the Scandinavian countries. The mustard sauce in which the fish fillets are baked in is super creamy.

    The addition of onions and pickles make this dish an amazing experience. You can whip this recipe up in less than 10 minutes active working time but your family will think you might stood an hour in the kitchen.

    Flounder fish fillets in creamy mustard sauce pin image.

    One stereotype of German cuisine is that fish is basically not existent on the menu, but Germany has a huge variety of tasty fish dishes that stem mostly from the coasts of Germany of the North Sea and the Baltic Sea.

    One of my favorite German street food is a Herringsbrötchen (herring roll), a simple snack with a crusty roll, pickled herring and finely chopped onion rings.

    Another amazing German fish dish are Matjes nach Hausfrauen Art, tender herring fillets in an amazing creamy sauce which are often served with crispy fried potatoes.

    Jump to:
    • Ingredients
    • Instructions
    • Substitutions
    • Variations
    • Equipment
    • Storage
    • Top Tip
    • Serve with
    • Recipe
    • Food Safety
    • Frequently Asked Questions

    Ingredients

    The dish can be made with a few simple ingredients but tastes like a gourmet dish from a fancy restaurant.

    Overview picture with recipe ingreidents: flounder fillets, yellow onion, bowl with cornichons, butter, sour cream, heavy cream, lemon, mustard, parsley, salt and pepper.
    • 3 pounds flounder fillets without skin
    • ½ lemon
    • salt & pepper
    • 1 tbsp. butter
    • 1 onion
    • 20 cornichon pickles or 6 large dill gherkins
    • 1 cup heavy cream
    • 1 cup sour cream
    • 6 tbsp. mustard
    • 1 tsp. coarse black pepper

    See recipe card for quantities.

    Instructions

    This dish will be prepped in less than 10 minutes. It´s best to start with preheating the oven to 350°F..

    Clean Flounder, drizzle with lemon juice, and salt and pepper on both sides.

    In the meantime, clean your fish and squeeze the juice of half of a lemon over the fish fillets.

    Then butter a casserole dish and place the fish fillets in one layer into the pan. You need perhaps two casserole dishes, depending on the size of your fish fillets and your casserole dish.

    Then salt and pepper the fish fillets on both sides.

    Add sour cream and heavy whipping cream to a small bowl and whisk the mustard into the liquid.

    Mix sour cream, heavy cream and mustard in a small mixing bowl to a smooth consistency.

    creamy mustard sauce with onions and pickles

    Finely chop onion and the cornichon pickles and add them with the coarse black pepper to the mustard sauce.

    pouring mustard cream sauce over fish fillets in a casserole dish.

    pour your mixture over the fish fillets and spread it out evenly.

    Substitutions

    This dish is also suited for low carb and ketogenic diets. Here are some substitutions if you would like to lower the calorie count or adjust to your own taste.

    • Heavy Cream - instead of heavy cream you can use half and half.
    • Cornichon Pickles - if you can´t find cornichon pickles, use bread and butter pickles or dill gherkins. If you are on a low carb diet make sure that your pickles don´t have added sugar.
    • Flounder Fillets - the dish also works well with other fish varieties i.e. Tilapia, Walleye or Swai.

    Variations

    Try these variations to make this dish more to your liking.

    • Spicy - add banana pepper rings instead of pickles to the sauce.
    • Deluxe - Use king prawns instead of fish fillet. It is best to butterfly the prawns before placing them into the casserole dish.
    • Garlic - add a teaspoon of garlic paste to the sauce.

    See this recipe for homemade garlic paste on my website! It is easy to prep, way cheaper than store bought garlic paste and tastes like you added freshly chopped garlic to the dish.

    Equipment

    I use my cheap Ikea glass casserole dishes for this recipe, but you can use stoneware for this dish too.

    Storage

    This dish can be re-heated but is not the best for freezing or meal prep. But you can make the sauce ahead of time and allow the fish fillets to defrost in the morning. This way your dish is ready to go into the oven in just a couple of minutes.

    Top Tip

    Make sure to butter the sides of the dish too, as this will make clean up so much easier.

    Serve with

    Serve with a German Salzkartoffeln (boiled potatoes), rice or mashed potatoes and a vegetable side dish. My favorite veggie sides are broccoli or this peas & carrots dish with buttery bread crumbs.

    Recipe

    flounder fillets in creamy mustard sauce with a side of broccoli

    Quick Flounder Fish Fillets In Creamy Mustard Sauce

    Angela Schofield
    This delicious German fish recipe is super quick and easy to make but tastes like a gourmet dish.
    5 from 1 vote
    Print Recipe Share on Facebook Pin Recipe
    Prep Time 10 mins
    Cook Time 15 mins
    Course Entrees
    Cuisine German
    Servings 6 portions
    Calories 410 kcal

    Equipment

    • 1-2 Casserole Dish(es)

    Ingredients
      

    • 3 pounds flounder fillets without skin
    • ½ lemon
    • salt & pepper to taste
    • 1 tbsp. butter
    • 1 onion
    • 20 cornichon pickles or 6 large dill gherkins
    • 1 cup heavy cream
    • 1 cup sour cream
    • 6 tbsp. mustard
    • 1 tsp. coarse black pepper

    Instructions
     

    • Preheat oven to 350°F.
    • In the meantime, clean flounder fillets and squeeze the juice of half of a lemon over the fish fillets.
    • Butter a casserole dish and place the fish fillets in one layer into the pan.
    • Salt and pepper on both sides.
    • Add sour cream and heavy cream to a small bowl and mix with mustard.
    • Finely chop onion and cornichon pickles and add with the coarse black pepper to the bowl.
    • Mix well and pour over the fish fillets.
    • Bake for about 15-20 minutes.

    Notes

    Serve with a boiled potatoes, rice or mashed potatoes and a vegetable side dish.

    Nutrition

    Calories: 410kcalCarbohydrates: 6gProtein: 31gFat: 29gFiber: 1gSugar: 2g
    Tried this recipe?Let us know how it was!

    Food Safety

    • Wash hands after handling raw fish
    • Don't re-freeze thawed fish.

    See more guidelines at USDA.gov.

    Frequently Asked Questions

    What temperature should flounder fillets be cooked to?

    Flounder is a very delicate fish. Cook the fish fillets to a temperature between 140 °F (60 °C) to 145 °F (63 °C)

    How to avoid baked flounder from being mushy?

    Thin sided fish like flounder can get mushy if it is watered for too long. The same can happen if you drizzle the fillets with lemon juice and let them marinate for too.

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    Angela framed by German landscape

    Guten Tag, I'm Angela,
    Herzlich willkommen! I'm glad you've stopped by.

    It is a joy to share with you some of my all-time favorite authentic German recipes and tell you a little bit about the cultural background of my home country, Germany.

    More about me →

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