Learn how to cook the perfect New Zealand grass-fed Wagyu steak in a cast iron skillet. Serve the steak with creamy French onion mushrooms for an elegant, flavorful dinner.
Sponsored by Beef + Lamb New Zealand and First Light.
This recipe is designed to impress while staying simple enough for a weeknight or special occasion. New Zealand 100% grass-fed Wagyu from First Light offers excellent marbling, yielding a tender, buttery steak with subtle sweet and nutty notes. Because these cattle are grass-fed year-round and raised without routine antibiotics or added hormones, the meat delivers clear, natural flavor and a clean finish.
Grass-fed Wagyu benefits from a low-stress, pasture-based life that contributes to tenderness and taste. When cooking this beef, the marbling provides natural flavor and a delicious crust when seared, so you don’t need heavy fats or complicated techniques. With just a sprinkle of coarse sea salt and freshly cracked black pepper, a hot cast iron skillet, and careful timing, you can achieve a restaurant-quality steak at home.
In this recipe, a New York strip from First Light is seared in a cast iron skillet and paired with Creamy French Onion Mushrooms. The mushrooms’ savory, silky sauce complements the nutty richness of grass-fed Wagyu for a balanced plate: earthy mushrooms and caramelized onion notes alongside a perfectly cooked steak.
What is the best way to cook Grass-fed Wagyu Steak?
Searing grass-fed Wagyu in a hot cast iron skillet on the stove is the easiest and most reliable method. A quick, high-heat sear forms a flavorful crust, then lowering the heat briefly finishes the interior to the desired doneness.
Grass-fed Wagyu Steak Cooking Tips
- Bring steaks to room temperature. Remove steaks from the refrigerator about 60 minutes before cooking so they cook more evenly and finish faster.
- Keep seasoning simple. Coarse sea salt and freshly cracked black pepper are all you need to enhance the Wagyu’s natural flavor without overpowering it.
- Preheat the skillet thoroughly. Heat a cast iron skillet over high heat until very hot. Sear steaks 2 minutes per side to develop a crust, then reduce heat to medium-high and cook about 3 minutes per side, or until the internal temperature reaches your preferred doneness.
- Use a temperature guide. For best results, check internal temperature with an instant-read thermometer:
- 125°F — rare
- 130°F — medium-rare
- 140°F — medium
- 150°F — medium-well
- 160°F — well-done
- Let the steak rest. After cooking, loosely tent the steak with foil and allow it to rest 5–10 minutes so the juices redistribute for a juicier, more tender result.
What to serve with Grass-fed Wagyu Steak
New Zealand grass-fed Wagyu pairs beautifully with mushrooms and fresh greens. Peppery arugula or lightly dressed baby greens help cut the richness, while nutty or tangy condiments add contrast. Popular accompaniments include an arugula and blue cheese pesto or a bright chimichurri-style sauce. For this recipe, the recommended pairing is Creamy French Onion Mushrooms — their savory, silky sauce and caramelized onion flavor are a natural match.
How to make Creamy French Onion Mushrooms
Melt butter in a large skillet over medium-high heat. Add thinly sliced onions and sauté about 5 minutes, until they begin to soften and turn translucent. Add sliced baby bella (cremini) mushrooms, minced garlic, and a French onion dip seasoning mix; continue sautéing for another 5–6 minutes until the mushrooms release moisture and start to brown.
Sprinkle cornstarch over the vegetables, then add beef broth and simmer 1–2 minutes to thicken slightly. Reduce heat to low and stir in half-and-half; simmer about 6 minutes until the sauce is creamy and coats the mushrooms. Finish by stirring in grated Parmesan cheese, adjusting seasoning to taste, and serve warm alongside the seared Wagyu steak.
To learn more about 100% grass-fed Wagyu from New Zealand, search for Beef + Lamb New Zealand and First Light for additional information, cooking tips, and recipe ideas.
New Zealand Grass-fed Wagyu New York Strip Steak with Creamy French Onion Mushrooms
Learn how to cook the perfect New Zealand grass-fed Wagyu steak in a cast iron skillet and serve it with creamy French onion mushrooms for a flavorful, satisfying meal.
Servings: 2 people
Prep Time: 35 minutes
Total Time: 35 minutes
Author: Whitney Bond
Ingredients
Wagyu Steak
- 2 New Zealand grass-fed Wagyu New York strip steaks (approx. 12 oz each)
- 1 tsp coarse sea salt
- 1 tsp freshly cracked black pepper
Creamy French Onion Mushrooms
- 2 tbsp butter
- 1 cup thinly sliced onions
- 16 oz baby bella (cremini) mushrooms, sliced
- 3 cloves garlic, minced
- 1 tbsp French onion dip mix
- 2 tbsp cornstarch
- 1/2 cup beef broth
- 1/2 cup half-and-half
- 1/4 cup grated Parmesan cheese
Instructions
Grass-fed Wagyu Steak
- Remove the steaks from the refrigerator and let them come to room temperature for about 60 minutes.
- Season all sides with coarse sea salt and freshly cracked black pepper.
- Heat a cast iron skillet over high heat until very hot.
- Add steaks and sear 2 minutes per side to form a crust.
- Reduce heat to medium-high and continue cooking about 3 minutes per side, or until the internal temperature reaches your preferred doneness (see temperature guide above).
- Remove steaks from the skillet, loosely wrap in foil, and rest 5–10 minutes.
- Slice and serve immediately with the creamy mushrooms.
Creamy French Onion Mushrooms
- Melt butter in a large skillet over medium-high heat.
- Add onions and sauté 5 minutes until soft and lightly golden.
- Add mushrooms, garlic, and French onion dip mix; sauté another 5–6 minutes until mushrooms brown.
- Sprinkle cornstarch over the pan, add beef broth, and simmer 1–2 minutes to thicken.
- Reduce heat to medium-low, add half-and-half, and simmer 6 minutes until sauce is creamy.
- Stir in Parmesan cheese, adjust seasoning, and serve hot alongside the steak.
Notes
- Prepare the mushrooms while the steaks come to room temperature so they can simmer and stay warm while you sear the Wagyu.
- Use an instant-read thermometer to check doneness: 125°F rare, 130°F medium-rare, 140°F medium, 150°F medium-well, 160°F well-done.
- Calories and nutrition values are approximate and listed per serving.
Nutrition Facts (per serving, approximate)
- Calories: 1117 kcal
- Carbohydrates: 29 g
- Protein: 84 g
- Fat: 73 g
- Saturated Fat: 34 g
- Cholesterol: 333 mg
- Sodium: 1907 mg
- Potassium: 2326 mg
- Fiber: 2 g
- Sugar: 7 g
- Vitamin A: 665 mg
- Vitamin C: 7.8 mg
- Calcium: 357 mg
- Iron: 6.4 mg