45 min
Grilled Flank Steak Sandwiches with Caramelized Onions and Mushrooms
Recipe GLPR19966fa31f7695
Tender, marinated flank steak grilled to medium-rare perfection, piled onto toasted baguette halves with sweet caramelized onions, golden mushrooms, and melted white cheddar. Topped with a zesty horseradish-mayo spread and fresh tomato slices for a hearty, restaurant-quality sandwich.
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Ingredients
1½ lbs Flank steak
¼ cup Olive oil
3 Garlic cloves, minced
2 Tablespoons Red wine vinegar
⅓ cup Soy sauce
2 Tablespoons Honey
½ teaspoon Ground black pepper
1 Tablespoon Butter
2 Tablespoons Olive oil
1 Large yellow onion, thinly sliced
8 ounces Sliced mushrooms
pinch Salt
1 Large French baguette, cut into fourths
8 slices White cheddar cheese slices
¼ cup Mayonnaise
¼ cup Sour cream
2 Tablespoons Creamed horseradish spread
Sliced tomato
Directions
In a large ziplock bag or shallow baking dish, combine the minced garlic, red wine vinegar, soy sauce, honey, and ground black pepper. Add the flank steak and turn to coat evenly with the marinade. Seal the bag or cover the dish, then refrigerate for at least 2 hours, preferably overnight.
Remove the steak from the refrigerator and let it sit on the counter for 20–30 minutes to come to room temperature. Meanwhile, preheat your grill to medium-high heat, and place a cast-iron skillet on the grill to warm.
Add 1 Tablespoon of butter and 1 Tablespoon of olive oil to the hot skillet and let them melt together.
Add the thinly sliced onion and a pinch of salt to the skillet, tossing gently to coat with the butter-oil mixture.
Cover the grill with the lid and allow the onions to cook undisturbed for about 5 minutes. Stir well, then repeat this process two more times (stirring every 5 minutes), cooking for approximately 15 minutes total. If the onions begin to brown too quickly before becoming soft, add about 1 Tablespoon of water to prevent scorching.
Add the sliced mushrooms and the remaining 1 Tablespoon of olive oil to the skillet, stirring to combine. Continue cooking for 5–10 minutes more, stirring occasionally, until the onions are very soft and caramelized and the mushrooms are golden brown. Remove the skillet from the grill and set aside.
Place the marinated flank steak directly on the grill grates over the hottest part of the grill. Cook for 4–5 minutes on the first side without moving it.
Flip the steak and cook for an additional 4–5 minutes on the second side. The internal temperature should reach 145°F for medium-rare doneness. Remove the steak to a clean plate and allow it to rest for at least 10 minutes before slicing.
While the steak rests, preheat your oven's broiler to low heat.
Slice the baguette segments in half horizontally. Lightly butter the cut sides and toast them on the grill or under the broiler if desired, until golden and slightly crispy.
Slice the rested flank steak against the grain into thin strips. Layer each baguette bottom with steak slices, then top with a generous portion of the caramelized onions and mushroom mixture. Finish with 2 slices of white cheddar cheese on top.
Place the loaded sandwich bottoms under the broiler for 3–4 minutes, until the cheese is fully melted. Meanwhile, whisk together the mayonnaise, sour cream, and creamed horseradish spread in a small bowl until smooth.
Remove the sandwiches from the broiler and spread the horseradish-mayo mixture on the toasted baguette tops. Arrange fresh tomato slices on top of the melted cheese on each sandwich, then close the sandwiches and serve immediately.
