Table of Contents

Flank Steak in Mushroom Wine Sauce: A Slow-Cooker Sensation

My grandmother, bless her heart, wasn’t known for her gourmet cooking. But she had a handful of dishes that were legendary in our family, and this flank steak in mushroom wine sauce was one of them. I remember the intoxicating aroma that would fill her small kitchen on Sunday afternoons, a blend of savory beef, earthy mushrooms, and a subtle hint of wine. We’d gather around her table, eager to sop up every last drop of that flavorful sauce with chunks of crusty bread. It wasn’t fancy, but it was love on a plate. And now, I’m sharing it with you.

Recipe Overview

Prep Time: 15 minutes
Cook Time: 6 hours 20 minutes to 7 hours 30 minutes
Total Time: 6 hours 35 minutes to 7 hours 45 minutes
Servings: 4-6
Dietary Type: Omnivore

Ingredients

1 – 1 1⁄2 lb beef flank steak
1⁄4 cup sauterne white wine (a regular dry white wine can be used, but sauterne adds a unique sweetness)
1 tablespoon soy sauce
1 garlic clove, minced
10 1⁄2 ounces condensed beef broth
1 tablespoon ketchup or 1 tablespoon tomato paste
1 tablespoon prepared mustard
1 small onion, finely chopped
3 tablespoons cornstarch
1⁄4 cup water
1⁄2 lb fresh mushrooms, sliced

Equipment Needed

Crockpot (slow cooker)
Small bowl
Saucepan (optional, for faster sauce thickening)

Instructions

Place the flank steak directly into the crockpot. This will be your cooking vessel for the next several hours, so make sure your steak fits comfortably.
In a separate small bowl, prepare the sauce. Combine the sauterne white wine, soy sauce, minced garlic, condensed beef broth, ketchup (or tomato paste), prepared mustard, and finely chopped onion. Whisk these ingredients together until they are well blended.
Pour the sauce mixture evenly over the flank steak in the crockpot, ensuring that the steak is mostly submerged in the liquid.
Cover the crockpot with its lid and set it to cook on the low setting for 6 to 7 hours. The long, slow cooking time is what transforms the flank steak into a melt-in-your-mouth delicacy, allowing the flavors to meld beautifully.
After the initial slow cooking period, turn the crockpot to the high setting. This will help to thicken the sauce.
In a small bowl, create a slurry by dissolving the cornstarch in the water. Stir until there are no lumps. This slurry will act as a thickening agent for the sauce.
Pour the cornstarch slurry into the crockpot, stirring it gently into the sauce. Add the sliced fresh mushrooms.
Cover the crockpot again and continue cooking on high for an additional 20-30 minutes, or until the mushrooms are tender and the sauce has thickened to your desired consistency.
Before serving, carefully remove the flank steak from the crockpot and place it on a cutting board. To ensure maximum tenderness, slice the meat thinly across the grain. This is a crucial step, as cutting with the grain can result in a tougher, chewier texture.
Serve the sliced flank steak with the delicious mushroom wine sauce spooned generously over the top.

Note: If you’re in a hurry, you can expedite the sauce-thickening process. After removing the meat to a plate and covering it with foil to keep it warm, transfer the sauce from the crockpot to a saucepan. Heat the sauce over medium-high to high heat, stirring constantly, until it reaches your desired thickness. This method is significantly faster than thickening the sauce directly in the crockpot.

Expert Tips & Tricks

For a richer flavor, consider browning the flank steak in a skillet with a little oil before placing it in the crockpot. This adds an extra layer of caramelized goodness.
Don’t skip the sauterne! While dry white wine works, the touch of sweetness in sauterne elevates the sauce to a whole new level.
If you want to add even more depth to the sauce, add a splash of Worcestershire sauce along with the other ingredients.
To prevent the mushrooms from becoming too soft, you can add them during the last 15 minutes of cooking instead of 20-30.
If the sauce is too thick, add a bit more beef broth or water to reach the desired consistency.
The meat should easily pull apart when it’s done. If it’s still tough, continue cooking for a little longer.

Serving & Storage Suggestions

Serve this flank steak in mushroom wine sauce with a side of mashed potatoes, rice, or egg noodles to soak up all that delicious sauce. Steamed green beans or a simple salad would also complement the dish nicely.

Leftovers can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, gently warm the steak and sauce in a saucepan over low heat, or microwave in short intervals until heated through. The sauce may thicken upon refrigeration, so you may need to add a little water or broth when reheating. Freezing is not recommended as it can affect the texture of the mushrooms.

Nutritional Information

Nutrient	Amount per Serving	% Daily Value
Calories	311.7 kcal	N/A
Calories from Fat	98 g	31%
Total Fat	10.9 g	16%
Saturated Fat	4.4 g	21%
Cholesterol	57.8 mg	19%
Sodium	787.7 mg	32%
Total Carbohydrate	12.3 g	4%
Dietary Fiber	1.1 g	4%
Sugars	3 g	11%
Protein	37.2 g	74%

Note: Nutritional information is an estimate and may vary based on specific ingredients and serving sizes.

Variations & Substitutions

Gluten-Free: Ensure the soy sauce and beef broth are gluten-free. Tamari can be used as a soy sauce substitute.
Vegetarian/Vegan: While this recipe features flank steak, you could adapt the mushroom wine sauce to serve with grilled portobello mushrooms or firm tofu for a vegetarian/vegan option. You would also need to substitute the beef broth with a vegetable broth.
Wine Variation: Experiment with different types of white wine to adjust the flavor profile. A dry sherry or Marsala wine could also be interesting substitutes for the sauterne.
Herb Enhancement: Add fresh herbs like thyme or rosemary to the crockpot for an aromatic boost.

FAQs (Frequently Asked Questions)

Q: Can I use frozen flank steak for this recipe?

A: Yes, you can use frozen flank steak, but be sure to thaw it completely before placing it in the crockpot for even cooking.

Q: Can I use dried mushrooms instead of fresh ones?

A: Yes, but rehydrate them in warm water before adding them to the crockpot. This will give them a more pleasant texture.

Q: What if I don’t have sauterne wine?

A: A dry white wine such as Pinot Grigio or Sauvignon Blanc can be used, but the sauterne adds a subtle sweetness that complements the dish beautifully. You could also add a teaspoon of sugar to the dry white wine.

Q: Can I make this recipe in the Instant Pot?

A: Yes, you can adapt this recipe for the Instant Pot. Brown the steak first, then add the remaining ingredients and cook on high pressure for about 25-30 minutes, followed by a natural pressure release for 10 minutes.

Q: The sauce is too thin, even after thickening. What can I do?

A: You can add a little more cornstarch slurry (1 tablespoon cornstarch mixed with 2 tablespoons cold water) and continue cooking until the sauce reaches your desired consistency.

Final Thoughts

This Flank Steak in Mushroom Wine Sauce is a true comfort food classic, easy enough for a weeknight meal yet elegant enough for a special occasion. Don’t be afraid to experiment with the variations and substitutions to make it your own. I encourage you to try this recipe and share your creations with friends and family. Pair it with a simple salad and a glass of your favorite wine for a complete and satisfying meal. Happy cooking!

Flank Steak in Mushroom Wine Sauce Recipe