With its robust flavor, tender texture (when sliced correctly), and simple geometry, flank steak is a great cut to cook hot and fast in a skillet or on the grill [1]. Seared, marinated, and thinly sliced, flank steak can hold its own as a main dish, and is also a welcome addition to salads or wraps. One of my favorite applications of flank steak is a sandwich—particularly if a friend just baked a loaf of homemade sourdough!

Ingredients

***For the Steak***
1 lb flank steak
½ cup Worcestershire sauce
½ cup vegetable oil
4 cloves garlic
1 tbsp brown sugar
1 tbsp Dijon mustard
Salt
Black pepper

Prepare a simple marinade for the steak by combining the Worcestershire sauce, brown sugar, Dijon mustard, and ½ cup of vegetable oil. Mix the marinade together, and smash the garlic cloves with the flat of a knife. Place the steak in a gallon zipper bag, together with the garlic cloves, and pour over the marinade. Press all of the air out, and seal the bag. Place the bag in secondary containment, and let the steak marinate in the refrigerator for at least 4 hours, and up to overnight.

While the flavors of a marinade don’t penetrate far into meat, flank steak is a cut which responds very well to marinades because of its thin geometry and high surface area to mass ratio. This recipe uses 1 pound of flank steak, which is about half to a third of a typical flank steak. This is a reasonable size for fitting into a skillet, but if you are grilling, feel free to use a larger steak. The cook times will be the same, since flank steak is pretty uniform in thickness, but increase the quantity of marinade you make accordingly.

When you are ready to cook the steak, remove it from the marinade, and pat it dry of excess marinade with a paper towel. Season both sides liberally with salt and black pepper, and let the steak air dry for 20 minutes at room temperature. This helps draw moisture out of the exterior surface, resulting in a better sear. It also raises the interior temperature of the steak to closer to room temperature, allowing the meat to cook more gently and evenly. [2]

When ready to sear, heat a tablespoon of vegetable oil in a stainless steel or cast iron skillet. When the vegetable oil just begins to smoke, add the steak to the pan. Let the steak sear for 2 minutes without moving it, so that it develops a crust. Then flip the steak to sear the other side. Insert a probe thermometer in the center of mass of the steak, making sure that the tip of the thermometer is halfway through the thickness of the steak. Sear on the second side for 2-3 minutes, or until the desired target temperature is reached.

Flank steak is served best at medium rare. For medium rare, the target pull temperature should be 125° F in the pan, which will coast up to a service temperature of 130° F while resting. If you’re grilling, follow the same timing procedure—cook for three minutes per side over hot coals or high heat, until the steak reaches the desired internal target temperature.

When the steak is ready to be removed from the heat, wrap it tightly in two layers of aluminum foil. The foil allows the temperature in the resting meat to coast up more quickly and then drop more slowly, making the resting period more effective for retaining juices. The steak should rest in the foil for at least 10 minutes before slicing.

Ingredients

***For the Sandwich***
Sliced flank steak
8 slices sourdough bread
¼ cup roasted garlic aioli
4 oz arugula
4 oz pickled red onions

While the steak is resting, we can prepare the other ingredients of our sandwiches. Sourdough brings a more complex flavor to the sandwich, helping to balance the richness of the beef and aioli. We want our bread to be warm, but not dry. Warm the bread either in the oven or the microwave. If you’re using an oven, preheat it to 350° F. Wrap the slices of bread together in aluminum foil, to prevent browning and retain moisture. Then bake in the oven for 10 minutes, until the bread is warmed through. If you’re using the microwave, cover the slices of bread in a damp paper towel, and microwave in two or three 30 second pulses, until the bread is warm.

Spread our garlic aioli onto the slices of bread. Two of our sandwich components, the beef and the aioli, are rich and savory, and we seek to counterbalance this with our other ingredients. Fresh arugula adds a peppery, bitter note which pairs well with steak [3], and pickled red onions will bring crunch, color, and acid, helping to cut through the richness. Lay the arugula leaves on the bottom halves of the sandwich.

When our steak is rested, it is time to slice. Because of the distinctive muscle structure of flank steak, it is critical to cut it perpendicular to the grain. This minimizes the length of the fibers in each piece of meat, resulting in a more tender texture when chewing. Cut the steak against the grain into ¼ inch thick slices.

Lay the slices of steak on top of the arugula. Top the steak with pickled onions, and complete the sandwich with the top slice of bread.

Substitutions

Country bread works well if you don’t like sourdough. However, avoid soft or sweet breads for this sandwich. Sandwiches are very flexible when it comes to toppings, but endive in particular works well in lieu of arugula in steak sandwiches, as it brings a similar bitterness.

This method of cooking flank steak also works well for skirt steak, a cut with a similar grain structure and composition. Soy sauce works well as a substitute for Worcestershire sauce, but because it is saltier, use about a third of a cup of soy sauce per pound of steak.

[1] Flank steak is cut from the abdominal muscles of the cow. In France, this cut is known as bavette, which translates to “bib.”

[2] For a more detailed discussion of retaining moisture when searing steak, refer to our post on steak au poivre.

[3] The scientific name of arugula is Eruca sativa. “Arugula,” as this vegetable is called in American and Canadian English, is derived from the Italian “rucola,” a diminutive of the Latin “eruca.” In British English, this vegetable is called “rocket,” which actually comes from the same root. “Rocket” is derived from the French “roquette,” their diminutive for “eruca.”

Recipe

Prep Time: 10 min Cook Time: 6 min Total Time: 26 min
(+12 hrs inactive) (1 day)

Difficulty: 3/5

Heat Sources: 1 burner

Equipment: plastic zipper bag, skillet (steel or cast iron), aluminum foil, probe thermometer (optional)

Servings: 4

Ingredients

For the Steak
1 lb flank steak
½ cup Worcestershire sauce
½ cup vegetable oil
4 cloves garlic
1 tbsp brown sugar
1 tbsp Dijon mustard
Salt
Black pepper

For the Sandwich
8 slices sourdough bread
¼ cup roasted garlic aioli
4 oz arugula
4 oz pickled red onions

Instructions

1. Mix the Worcester sauce, brown sugar, Dijon mustard, and vegetable oil together to form a marinade. Smash the garlic cloves.

2. Place the flank steak in a large zipper storage bag, add the garlic cloves, and pour over the marinade. Seal the bag, and let marinade in the refrigerator for 4-12 hours.

3. Remove the marinated flank steak from the bag, and pat dry with paper towels. Season both sides with salt and black pepper, and allow the steak to air dry at room temperature for 20 minutes.

4. Heat 1 tbsp of vegetable oil in a large skillet or cast iron pan over high heat. As soon as the oil begins to smoke, add the steak to the pan. Sear 2-3 minutes per side (medium rare), or to your desired doneness.

5. Remove the steak from the heat, and wrap tightly in aluminum foil. The target internal temperature for medium rare is 125° F in the pan, which will coast up to a service temperature of 130° F while resting. Let the steak rest for at least 10 minutes before serving.

6. While the steak is resting, prepare the bread for the sandwiches. Warm the bread, and spread the slices with roasted garlic aioli. Lay arugula on the bottom halves of the sandwiches.

7. When the steak is done resting, slice it against the grain into ¼ inch slices.

8. Lay steak over the arugula, top with the pickled onions and complete the sandwich the top slice of bread.