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Grilled Wagyu Beef Flat Iron Steak with Yukon Gold Hasselback Potatoes

Balsamic and Rosemary Grilled Fullblood Wagyu Beef Flat Iron Steak with Yukon Gold Hasselback Potatoes

Recipe provided by Chef Melanie Hammericksen

Prep Time: 20 Minutes (Plus 6-12 hours to marinate)
Cook Time: 70 Minutes
Servings: 6
Difficulty Level: 2  (Levels: 1-5 with 5 being most difficult)


  • 1 Double 8 Cattle Company Fullblood Wagyu Beef Flat Iron Steak
  • 5 Garlic Cloves (minced)
  • 1/3 CUP Extra Virgin Olive Oil
  • 1/2 CUP Balsamic Vinegar
  • 2/3 CUP Red Wine
  • 2 TBSP Fresh Rosemary (chopped)
  • 1 TSP Kosher Salt
  • 1/2 TSP Freshly Ground Black Pepper

Yukon Gold Hasselback Potatoes

  • 6 Large Yukon Gold Potatoes (rinsed and patted dry)
  • 6 OZ Unsalted Butter (melted)
  • 3 Garlic Cloves (minced)
  • 3 SPRIGS Fresh Thyme Leaves (pick the leaves off one sprig and leave the other sprigs whole)
  • 2 TSP Kosher Salt
  • 1 TSP Freshly Ground Black Pepper
  • 4 OZ Parmesan (grated)
  • 4 TBSP Chives (chopped)


  • BBQ or Gas Grill
  • Chopsticks
  • Pastry Brush
  • Skillet
  • Parchment Paper


In a bowl, whisk together the minced garlic, extra virgin olive oil, balsamic vinegar, red wine, chopped rosemary, kosher salt, and freshly ground black pepper. This is your marinade.

Place the Fullblood Wagyu beef flat iron steak in a casserole dish.

Pour the marinade over the top of the steak. Flip and turn the steak in the marinade to fully coat.

Refrigerate the dish for 6-12 hours, turning the flat iron steak every few hours.

Pull the marinated steak from the refrigerator, and let it sit at room temperature for one hour.

When you’re ready to cook, preheat your grill to medium-high heat.


Preheat the oven to 400°F.

Melt the unsalted butter with the two whole sprigs of thyme, minced garlic, kosher salt, and freshly ground black pepper. This is your melted butter mix.

Place two chopsticks along each long side of a potato (the chopsticks act as a stopgap, keeping you from cutting all the way through the potato).

Using a chef’s knife, cut the potato down to the chopsticks, cutting 1/4-inch-thick slits all the way down the length of the potato. Do this cutting process on all of the potatoes.

Place the potatoes on a baking dish with parchment paper, and brush the potatoes with half of the melted butter mix.

Bake the potatoes for 35 minutes, then brush with the remaining melted butter mix.

Continue baking the potatoes until they are cooked through (about 30 minutes more).

Sprinkle with thyme and parmesan, and bake the potatoes for 5 more minutes.

Finish the potatoes by sprinkling chopped chives on top.


Place the Fullblood Wagyu beef flat iron steak on the preheated grill, and reserve the marinade.

Grill the steak for 5 minutes per side for a medium-rare finish. Remove the steak from grill, and let it rest for 10 minutes.

Meanwhile, pour the reserved marinade into a skillet over medium heat. Bring the marinade to a boil, and allow it to cook until it reduces by half (takes around 10 minutes). Watch the marinade closely so it doesn’t burn.

Spoon the marinade/sauce onto a serving plater. Slice the steak against the grain into 1/4-inch-thick slices, and place on top of the sauce.

Pair the steak with the Yukon Gold hassleback potatoes, and enjoy!

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