Open-Face Grilled Flank Steak Sandwiches with Mustard Sauce

Elevate your next cookout with these Open-Face Grilled Flank Steak Sandwiches. Tender, marinated flank steak is grilled to perfection, then layered over toasted sourdough with creamy herbed cheese, crisp greens, and a bright mustard sauce. A refined yet approachable meal that’s perfect for entertaining or an elevated weeknight dinner.

Recipe Information

Total Time:

Yield:

12 servings

Ingredients

Marinated steak

1 (1½- to 2-pound) beef flank steak

1 teaspoon kosher salt

1 teaspoon coarsely ground black pepper

½ cup coarsely chopped and tightly packed Italian parsley

2 tablespoons coarsely chopped fresh rosemary

6 cloves garlic, minced

2 tablespoons fresh lime juice

2 tablespoons Worcestershire sauce

½ cup extra-virgin olive oil

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Mustard sauce

¼ cup whole-grain mustard

2 tablespoons sour cream

2 tablespoons fresh squeezed lime juice

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Sandwiches

12 (½-inch-thick) slices Sourdough Bread

2 (6.5-ounce) packages garlic-and-herb spreadable cheese

Baby arugula and spinach mix, for garnish

Thinly sliced red onion

Thinly sliced red radishes

Arugula microgreens, for garnish

Coarsely ground black pepper, for garnish

Directions

For marinated steak, trim fat from steak, if necessary. Season with salt and pepper. Place steak in a large resealable plastic bag; set aside.
For marinade, in a food processor, place parsley, rosemary, garlic, lime juice and Worcestershire sauce. Cover and process until smooth. With the food processor running, slowly add olive oil in a thin, steady stream. Pour herb mixture over steak; seal bag. Turn bag to evenly coat steak. Marinate in the refrigerator for 6 to 24 hours, turning bag occasionally.
For mustard sauce, in a small bowl, stir together mustard, sour cream and lime juice; refrigerate until ready to serve.
Preheat grill for direct grilling over high heat (475°F). Remove meat from marinade; discard marinade. Grill steak for 15 to 20 minutes or until steak reaches 135°F for medium-rare doneness, rotating every 3 minutes and turning over halfway through. Transfer steak to a cutting board; cover loosely with foil and let stand for 2 minutes. Internal temperature will increase 10°F.
For open-face sandwiches, grill bread slices until lightly toasted on both sides. Thinly slice steak across the grain.
To assemble, spread one side of each bread slice with 1 tablespoon spreadable cheese; top with arugula and spinach mix. Place 3 to 4 slices of steak, onion and radishes on top of greens. Drizzle with mustard sauce. Garnish with microgreens and pepper, if desired.