Keto Filet Mignon with Mushroom and Mustard Sauce

This recipe for Keto Filet Mignon with Mushroom and Mustard Sauce is an elevated and elegant dinner that’s easier than it looks, low-carb and packed with savory, creamy flavors and textures.

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Hey Foodies!

I’ve been craving a delicious beef fillet recipe lately. So I thought, why not make a delicious steak with mushroom sauce that’s also keto-friendly? This recipe is a total crowd-pleaser and always impressive on the plate. And the best part is that it’s easy to make on a weeknight, but tastes like it was served by a 5-star restaurant.

Ready to learn how to make the best filet mignon recipe? First, read on for the best Tips & Tricks to make delicious Keto Filet Mignon with Mushroom Sauce.

Tips & Tricks for the Best Filet Mignon Recipe

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1. Which ingredients can be changed in this Keto Filet Mignon Recipe?

If you’d like to tweak this recipe a bit to suit your tastes or dietary preferences, it’s easy!

For dairy-free fillet mignon with mushroom sauce, sub the heavy cream with the same amount of non-dairy milk. To help thicken up your sauce, whisk in 1 tbsp cornstarch or flour. You can also use gluten-free all-purpose flour for this.

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If you prefer a different flavor rather than mustard, simply swap out the mustard with a nice aged balsamic vinegar. The whole vibe of this dish will change into a dark, sweet caramel-scented dish that’s truly delicious and worth trying, even if you love mustard!

In fact, you can swap out the steak altogether and make this recipe with chicken or turkey cutlets. To do so, follow the same recipe, but cook the poultry cutlets longer, around 6-8 minutes per side, or until no longer pink on the inside. The internal temperature should read 165°F (74°C).

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And the mushrooms for the sauce, oh so many possibilities! You can experiment with any mushrooms you like or have on hand. Me, I simply love all mushrooms, especially when you mix several varieties together. Some of my absolute favorite mushrooms to use in this creamy mustard sauce are:

  • Button
  • Crimini
  • Portobello
  • Porcini
  • Oyster
  • King oyster

You can also use a mix of wild mushrooms. YUM!

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2. Best way to cook Keto filet mignon with mushroom sauce

To make the best filet mignon, I recommend using your stove as described in the recipe. A hot pan sears the steak absolutely perfectly. Before you cook, make sure to pat the steaks dry to remove as much moisture as possible. Also, season both sides well with salt and pepper. This adds flavor and helps dry the surface of the fillets well for better searing.

Here’s how to do sear perfect filet mignon for this recipe:

  1. Heat 1 tablespoon of oil in a large skillet over medium-high heat.
  2. When the pan is very hot, add in the beef filets and cook undisturbed for 3-4 minutes on each side.
  3. The cooking time varies a lot depending on the thickness of your fillets. I used 1-inch thick fillets and cooked them for 3 min per side for rare. It’s best to cook them rare and then continue to cook in the sauce a bit more.

Surely, there are other ways to cook your keto steak with mushroom sauce too, as I’ll explain below.

Important note: the steak should always be cooked from room temp. Let it sit on the counter for 30 minutes before cooking!

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3. How to grill filet steak?

If you’re planning to cook outside on a beautiful day, this is a great recipe to use.

To grill your keto filet steak:

  1. Preheat a grill pan or the outside grill on medium-high heat.
  2. Add the filets and cook undisturbed for 3-5 minutes per side.

4. How to fry filet mignon?

A third way to cook this filet with keto mushroom sauce is to fry it.

To make fried filet mignon:

  1. Heat 1 tablespoon of oil in a large skillet over medium-high heat. Don’t overdo it with the oil though, 1 tbsp is more than enough.
  2. Add the beef filets and cook undisturbed for 3-4 minutes on each side. The cooking time varies a lot depending on the thickness of your fillets.

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5. How to season filet mignon for the grill?

This keto filet mignon with mushroom sauce doesn’t really need pre-grilling seasoning. Especially because the mushroom and mustard sauce is so delicious and flavorful on its own.

I actually prefer to season my steak right after cooking or grilling it. And more is less when it comes to steak.

A simple sprinkle of Maldon flaky sea salt and some freshly cracked black pepper is more than enough for this tasty meat. If you like your steak even more flavorful, then you could try a chimichurri sauce. See this chimichurri chicken salad for the best chimichurri sauce.

6. How to marinate filet mignon for grilling?

Speaking of chimichurri, it also makes a great marinade for this steak. For something that also pairs well with the mushroom and mustard sauce, try a quick marinade of:

  • Olive oil
  • Mustard
  • Garlic
  • Lemon juice
  • Fresh herbs, like tarragon or rosemary

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7. What temperature to cook filet steak?

Here are the internal temperatures to cook your filet to, depending on how done you like your meat:

Rare steak: 125°F/52°C.

For medium-rare: 135°F/57°C

Medium: 145°F/63°C

Medium Well: 150°F/66°C

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More Keto Recipes

And that was it for today, my dear foodies. By now, I am sure you know how to make the best filet mignon recipe, so let’s get to the cooking!

And if you like this keto filet mignon recipe video and want to see more like it, please Subscribe to my YouTube Channel.

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5 from 1 vote

Keto Filet Mignon with Mushroom and Mustard Sauce

This Keto Filet Mignon with Mushroom Sauce is creamy, savory and restaurant-quality but easy to make at home for a low-carb dinner.
Course dinner
Cuisine American, French
Prep Time 12 minutes
Cook Time 28 minutes
Total Time 40 minutes
Servings 4
Calories 731kcal
Author Mihaela

Ingredients

  • 2 tbsp olive oil - divided
  • 4-6 filet mignon steaks - (about 1 1/2" thick, 4-ounce each), at room temperature
  • 1 tbsp butter
  • 1 yellow onion - finely diced
  • 2-4 medium garlic cloves - minced
  • 1 container (14oz / 400g) baby brown mushrooms - cleaned
  • 1/2 cup low-sodium beef broth
  • 2/3 cup heavy cream
  • 1 1/2 tbsp mustard
  • 2 tbsp fresh curly parsley - chopped
  • Sea salt and ground pepper - to taste

Instructions

  • Heat 1 tablespoon of oil in a large skillet over medium-high heat.
  • Add in the beef filets and cook undisturbed for 3-4 minutes on each side. Set aside and cover to keep warm.
  • Add the remaining oil and butter to the skillet.
  • Once the butter is foamy, add the onion and sauté for 3-4 minutes until softened.
  • Stir in the garlic and mushrooms. Cook, stirring occasionally for about 5 minutes, or until the mushrooms are tender.
  • Add the broth to deglaze the pan, stirring to remove all the brown bits stuck at the bottom.
  • Simmer until the broth is absorbed, about 5-6 minutes. Stir in the cream and mustard.
  • Return the steak to the pan and heat it up for a couple of minutes.
  • Remove from heat, sprinkle with fresh parsley and serve.

Recipe Notes

Here is a summary of the best Tips & Tricks for my Keto Fillet Mignon Recipe:
  1. Tip #1 details the ingredients you can swap in the recipe.
  2. See Tip #2 for the best way to cook this tasty keto steak with mushroom sauce.
  3. If you want to make it on the grill, be sure to read Tip #3. 
  4. Tip #4 is about how to fry fillet mignon.
  5. See Tip #5 for how to season your fillet for grilling. 
  6. And if you have time to marinate the steak, read Tip #6 for a keto-friendly recommendation.

Nutrition

Calories: 731kcal | Carbohydrates: 9g | Protein: 35g | Fat: 62g | Saturated Fat: 27g | Trans Fat: 1g | Cholesterol: 181mg | Sodium: 258mg | Potassium: 1117mg | Fiber: 1g | Sugar: 3g | Vitamin A: 844IU | Vitamin C: 5mg | Calcium: 72mg | Iron: 5mg
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