Fish Fillets With Mushroom Sauce

Fish Fillets With Mushroom Sauce

The Spruce / Maxwell Cozzi

Prep: 15 mins
Cook: 25 mins
Total: 40 mins
Servings: 4 servings
Nutrition Facts (per serving)
361 Calories
14g Fat
12g Carbs
45g Protein
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Nutrition Facts
Servings: 4
Amount per serving
Calories 361
% Daily Value*
Total Fat 14g 18%
Saturated Fat 8g 39%
Cholesterol 197mg 66%
Sodium 545mg 24%
Total Carbohydrate 12g 5%
Dietary Fiber 1g 3%
Total Sugars 6g
Protein 45g
Vitamin C 4mg 21%
Calcium 159mg 12%
Iron 3mg 18%
Potassium 1227mg 26%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

Earthy mushrooms are a wonderful ingredient to add to your meals, as they offer a lot of texture and flavor, and can transform a bland dinner into a succulent dish. Our fish fillets with mushroom sauce is a simple recipe that is ready in just 40 minutes, perfect for a quick and easy family meal. Pair your preferred white fish fillet with your favorite mushroom, as the flavors will combine well regardless of what you choose. Ideally, opt for fresh fish, not previously frozen, and organic mushrooms for a better and fresher flavor. In a pinch, frozen-thawed fillets will also work well. Serve this easy recipe with rice or a rice pilaf to soak up the wonderful sauce; a crisp and cool green salad, asparagus, or roasted green beans; and some dinner rolls or savory scones.

The combination of mushrooms, onion, and thyme with sour cream and lemon juice is a scrumptious sauce for the tender and flaky fish. Cremini, button, brown, shiitake, or chanterelle mushrooms will be perfect for the dish. Arctic char, red snapper, cod, orange roughy, or any mild white fish is a great option for the fish, but favor what's freshest in the market. Your fillets should look shiny and bright in color—skip dull and grayish pieces. You want wet pieces, not sticky fillets, as that is a sign of old fish. As for the mushrooms, look for the ones with tightly closed gills—the underside of the mushroom cap—and smooth, unblemished caps. The stem should be tightly attached to the cap and the mushrooms should not be damp or soft, have fuzzy areas or any bluish discoloring.

Our sauce is also good over salmon or tuna steaks, chicken, beef roast, or sliced pork tenderloin. Any leftovers can be kept overnight, covered, in the refrigerator, and consumed within a day.


  • 2 tablespoons butter

  • 1 1/2 cups cremini mushrooms, sliced

  • 1 medium onionfinely chopped

  • 3 cloves garlic, minced

  • 2 tablespoons flour

  • 1 teaspoon dried thyme

  • 1/2 teaspoon salt

  • 1/8 teaspoon white pepper

  • 1 cup milk

  • 1/2 cup sour cream

  • 2 tablespoons lemon juice

  • 1 teaspoon lemon zest, grated

  • 1 1/2 pounds fish fillets

Steps to Make It

  1. Gather the ingredients.

    Fish fillets with mushroom sauce ingredients

    The Spruce / Maxwell Cozzi

  2. Preheat the oven to 350 F. Grease a 2-quart glass baking dish or spray it with nonstick cooking spray and set aside.

    Greased baking dish

    The Spruce / Maxwell Cozzi

  3. Melt the butter in a medium saucepan over medium heat.

    Butter melting in a saucepan

    The Spruce / Maxwell Cozzi

  4. When the butter starts to sizzle, add the mushrooms, onion, and garlic. Cook until the vegetables are tender, and the liquid evaporates, about 10 minutes, stirring frequently to prevent them from burning.

    Mushrooms, onion, and garlic in a saucepan

    The Spruce / Maxwell Cozzi

  5. Add the flour, thyme, salt, and pepper to the saucepan and cook for 2 minutes.

    Flour, thyme, salt, and pepper added to the mushroom mixture in the saucepan

    The Spruce / Maxwell Cozzi

  6. Add the milk and sour cream; cook and stir until the sauce is thickened and bubbly.

    Milk added to the mushroom gravy in the saucepan

    The Spruce / Maxwell Cozzi

  7. Remove the saucepan from the heat and add the lemon juice and zest.

    Lemon zest added to the mushroom gravy in the saucepan

    The Spruce / Maxwell Cozzi

  8. Place the fillets in the prepared baking dish and cover with sauce.

    Fish fillets with mushroom gravy on top in a baking dish

    The Spruce / Maxwell Cozzi

  9. Bake for 15 to 20 minutes or until the fish is cooked to at least 145 F inside and flakes easily when tested with a fork. Serve immediately with your favorite sides.

    Baked fish fillets with mushroom sauce in a baking dish

    The Spruce / Maxwell Cozzi

  10. Enjoy.

Gluten-Free Sauce and Garnish

  • Making this recipe gluten free is very easy. Simply replace in a 1:1 ratio the flour for white rice flour and add it at the same time as the method instructs.
  • You could add freshly chopped parsley on top of the fish right before serving for a pretty contrast in color.