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Guinness Marinated Flat Iron Steak

Yields1 ServingPrep Time1 hrCook Time10 minsTotal Time1 hr 10 mins

Flat Iron steak is my go to cut for a quick and inexpensive dinner. These steaks typically run about 5.99/lb at the grocery store so for around $12 you’ll have a steak that can feed 3-4 people easily. The flat iron is cut from the chuck area of the steer and has a similar texture to sirloin. It’s best cooked on the rare to mid-rare side, and as always, slice it across the grain for tender pieces.

 1 flat iron steak, 1.5 lbs
 1 tbsp Killer Hogs Steak Rub
Guinness Flat Iron Steak Marinade
 12 oz Guinness Stout Beer
 2 oz Worcestershire Sauce
 2 oz Soy Sauce
 1 tsp Killer Hogs AP Seasoning
Guinness Mushroom Sauce
 2 tbsp salted butter
 1 small shallot, finely chopped
 5 cloves garlic, minced
 8 oz baby bella mushrooms
 0.50 tsp kosher salt
 0.50 tsp black pepper
 ¼ cup soy sauce
 ¼ cup Worcestershire sauce
 1 tbsp balsamic vinegar
 1 cup Guinness Stout beer
 1 tsp corn starch
 1 tsp cold water

Remove flat iron steak from packaging and trim excess silver skin; place the flat iron in a 1-gallon size zip-top bag. Combine the ingredients for the marinade in a small bowl and pour over steak. Marinate for 1 hour.


Prepare charcoal grill for direct grilling at 500 degrees.


Prepare charcoal grill for direct grilling at 500 degrees. While grill is heating prepare Guinness Mushroom sauce: Melt butter in a sauce pan over medium heat. Add shallot and garlic and sauté for 2 minutes. Add sliced mushrooms and season with AP seasoning. Sauté for 2-3 minutes until mushrooms are tender. Add Worcestershire, soy, and balsamic reduce for 3-4 minutes; add Guinness and reduce volume by half (approx 5-7 minutes). Combine corn starch and cold water in a small bowl and whisk into sauce. Allow the mixture to reach a slight boil and remove from heat. Serve warm over steak.


Remove the flat iron steak from the marinade allowing excess moisture to drip back into the zip-top bag. Season the steak with Killer Hogs Steak Rub on all sides.


Place the steak on the grill and cook for 5 minutes. rotate the steak after 2.5 minutes to create grill marks. Repeat the same step for the opposite side for a total cook time of 10 minutes or until the steak reaches 125 internal temperature – medium-rare.


Rest the flat iron for 5-7 minutes before slicing and serve topped with Guinness Mushroom sauce.