Steak Sandwiches with Sauteed Mushrooms and Spinach

Prep Time:
30 mins
Total Time:
30 mins

With just a skillet, you can turn a classic steak dinner into a handheld affair.


  • 1 teaspoon vegetable oil

  • 2 New York strip (shell) steaks (8 ounces each)

  • Coarse salt and ground pepper

  • 1 medium yellow onion, thinly sliced

  • 8 ounces white button mushrooms, thinly sliced

  • 1 tablespoon red-wine vinegar

  • 1 bag (10 ounces) baby spinach

  • 4 teaspoons grainy or Dijon mustard

  • 8 slices crusty bread, toasted


  1. In a large skillet, heat oil over medium-high. Season both sides of steaks with salt and pepper. Cook steaks until medium-rare, about 5 minutes per side, flipping once. Transfer to a plate; tent loosely with foil to keep warm.

  2. Add onion to pan; season with salt and pepper. Cook until onion begins to soften, about 4 minutes. Add mushrooms; season with salt and pepper. Cook until mushrooms brown, about 6 minutes. Add vinegar and any accumulated juices from steaks; cook until evaporated, about 30 seconds. Transfer mushroom mixture to a medium bowl. Add spinach to pan; season with salt and pepper. Cook, stirring, until wilted, about 3 minutes.

  3. Thinly slice steaks against the grain. Spread mustard on 4 slices bread. Dividing evenly, top with sliced steak, mushroom mixture, and spinach. Top with remaining bread. Serve immediately.

Cook's Notes

You can substitute flank or skirt steak, but make sure to slice it very thinly against the grain.

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