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Jessica Secrest

Caramelized Onion & Flank Steak Sandwiches

Thin-sliced flank steak piled onto toasted hoagies with slow-cooked caramelized onions, melty white cheddar, and a cracked pepper-Parmesan mayo. Broiled just long enough to pull everything together.

⏱ 90 min4 servingssandwichesflank steakcaramelized onionsbeefcast iron

Ingredients

For the sandwiches

  • 1 lbflank steak
  • 1 TbspBasic ASS All-Purpose Seasoning Blend
  • 2 Tbspbutter
  • 2white onions · thinly sliced
  • —Salt and black pepper · to taste
  • 1 Tbspavocado oil
  • 4hoagies · or any other long-shaped bun you want
  • 1 cupshredded white cheddar cheese

For the cracked pepper-Parmesan mayo

  • 1/2 cupmayo
  • 1 tspDijon mustard
  • 1/2 tspblack pepper
  • 1/4 cupgrated Parmesan cheese

Steps

  1. 1

    Pull the steak out of the refrigerator about 20 minutes before you intend to cook it. Season both sides with the seasoning blend and press it into the meat, then wash your hands.

  2. 2

    Place a large cast iron skillet over medium-low heat. Once hot, add the butter and let it melt, then add the onions. It looks like a lot of onions, but they cook down significantly.

  3. 3

    Cook the onions, stirring occasionally, for about 45 minutes, until completely soft and golden brown. Be patient and don't turn the heat up.

  4. 4

    Transfer the onions to a bowl and return the pan to the heat. Don't wash it out — keep the onion flavor and remaining butter for the steak.

  5. 5

    Turn the heat up to medium-high and add the avocado oil. Once the oil is shimmering, add the steak.

  6. 6

    Cook the steak undisturbed for 4 minutes, then flip and cook 4 minutes more, or until the internal temperature reaches about 135°F for medium-rare.

  7. 7

    Remove the steak from the pan and let it rest on a cutting board for at least 10 minutes so the juices reabsorb.

  8. 8

    Mix all the cracked pepper-Parmesan mayo ingredients together in a small bowl.

  9. 9

    Slice the steak thinly against the grain so it isn't stringy or chewy.

  10. 10

    Open a hoagie and lay it flat on a baking sheet. Slather mayo on one side, then top with a few slices of flank steak, caramelized onions, and cheese. Repeat with the remaining hoagies.

  11. 11

    Broil the sandwiches for about 2 minutes with the baking sheet about 6 inches from the heat source, watching closely so they don't burn.

  12. 12

    Remove the pan from the oven as soon as the cheese begins to brown. Fold the sides of the bread together and serve.

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