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This mouth-watering steak sandwich piled high with tender grilled flank steak is dressed with a zesty horseradish aioli, fresh sliced tomatoes, and red onions served up on a grilled hoagie bun.
Season the steak with a homemade coffee rub made with pantry spices, then grill it to your desired doneness, and cut into thin slices. In just 30 minutes, you’ve got a hot gourmet sandwich that’s full of flavor, tender, and juicy. Grab the napkins and be sure to use two hands!
The BEST steak sandwich recipe
Don’t get me wrong, I love a good Philly cheesesteak sandwich loaded with grilled peppers and onions, but I must say this grilled flank steak sandwich is the absolute BEST!
The recipe is so simple, so flavorful, and definitely worth repeating often. In case you’re also looking for a good steak dinner recipe, let me recommend you check out this Cast Iron New York Strip.
The two secrets to the BEST steak sandwich? The coffee dry rub for the steak and the super easy homemade horseradish aioli. Talk about intense flavor!
What is flank steak?
Also commonly known as London Broil, this cut of beef comes from the cow’s underside below the loin. Lean and flavorful, flank steak is normally marinated for maximum tenderness. In today’s recipe, however, the coffee-flavored dry rub infused the meat with plenty of flavor and the cut remained extremely tender.
How do I make my steak juicy and tender?
- Let the meat set at room temperature a minimum of 15 minutes before tossing it on the hot grill. This ensures the meat cooks evenly.
- Don’t overcook the beef. Leave it on the grill too long and it will dry out. You want to preserve those flavorful juices! The perfect temperature for medium steak is 160 degrees.
- Let it rest before you slice it up. Remove the flank steak from the grill and loosely tent it with aluminum foil to rest for at least 5 minutes before you slice into it. This allows the juices to soak back into the meat for maximum juicy flavor.
- Slice the flank steak thinly and against the grain. Cut crosswise against the muscle fibers so they come apart easily and effortlessly as you chew.
Besides a smear of the horseradish aioli, here are my suggestions for dressing a steak sandwich:
- Sliced tomatoes
- Thinly sliced red onions
- Pickled red onions
- Caramelized onions or onion straws
- Pepperoncini peppers
What goes good with steak sandwiches?
What could be more perfect than steak and potatoes?! Here are a few of my favorite potato side dishes to serve with steak sandwiches. Oh, and I threw in a delicious onion ring suggestion, too!
- Grilled French Fries — Since you’ll have the grill going anyway, why not try these delicious hand-cut Grilled French Fries with Spicy Ketchup? They get nice and crispy on the outside and stay fluffy on the inside without a deep fryer!
- Oven Roasted Red Potatoes — Seasoned with rosemary, thyme, and garlic, these crispy Oven Roasted Red Potatoes are finished with a drizzle of quality aged balsamic vinegar.
- Roasted Red Potato Salad — This is my favorite go-to recipe for a quick and delicious picnic side dish.
- Crispy Oven Baked Onion Rings — Breaded with panko, these healthier onion rings are tender on the inside and nicely crisp on the outside.
To make this recipe, you may need…
You can gently press tongs into the cooked steak to determine its doneness with this touch test guide found with my Pan-Seared NY Strip recipe. To be totally accurate, however, use a quick read digital thermometer. I love my OXO Instant Read Thermocouple and use it for any kind of meat that I’m grilling or cooking indoors.
When grilling steaks, use tongs instead of a fork to turn the meat. Pierce the meat with a fork and you’ll run the risk of losing all the flavorful juices, so stick with a set of long-handled tongs.
Also, I like my steak prepared medium (about 160 degrees). Since steak continues to cook a little after it’s tented with aluminum foil to rest, I like to pull it off the grill at about 155 degrees.
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Steak Sandwich with Horseradish Aioli
- 1 1/2 pounds flank steak
- 6 soft hoagie buns
- 2 tablespoons extra-virgin olive oil
- 1 large tomato thinly sliced (optional)
- 1 small red onion thinly sliced (optional)
- 1 1/2 tablespoons ground dark roast coffee
- 3/4 teaspoon chili powder
- 1/2 teaspoon ground cumin
- 1/4 teaspoon sweet paprika
- 1/4 teaspoon kosher salt
- 1/4 teaspoon black pepper
- 2 tablespoons horseradish
- 2 tablespoons mayonnaise
- 1 tablespoon Dijon mustard
- 1/4 teaspoon kosher salt
- 1/8 teaspoon black pepper
- In a small bowl, stir together the horseradish, mayonnaise, Dijon mustard, salt, and pepper. Cover and refrigerate until ready to serve.
- In another small bowl, combine the coffee, chili powder, cumin, paprika, salt, and pepper to make the steak rub. Evenly sprinkle the rub mixture on both sides of the flank steak. Allow the teak to stand at room temperature for 15 (or up to 30) minutes before grilling.
- Preheat the grill to medium high heat, about 400 degrees. Brush the cooking grates clean, then brush with oil. Grill the steak over direct heat with the lid closed, turning once or twice, until cooked to your desired doneness — about 8 to 10 minutes for medium.
- Remove the steak from the grill and let rest for 5 minutes. While the meat rests, brush the cut sides of the bread with a light coating of olive oil. Place the buns cut side down over direct heat and cook a minute or two until lighted browned.
- Slice the steak across the grain into thin slices. Build the sandwich by spreading the horseradish aioli on one bun, then topping it with slices of steak, arugula, tomatoes, and red onions. Top with the remaining half of the bun and serve.
Life Love and Good Food does not claim to be a registered dietician or nutritionist. Nutritional information shared on this site is only an estimate. We recommend running the ingredients through an online nutritional calculator if you need to verify any information.
About Sheila Thigpen
Recipe Developer, Food Photographer, Food Writer
Sheila Thigpen is the publisher of Life, Love, and Good Food — a Southern food blog — and the author of Easy Chicken Cookbook and The 5-Ingredient Fresh and Easy Cookbook. After 20+ years in the publishing industry, she retired in 2018 to focus on her own creative endeavors full time. She and her husband live near the beautiful Smoky Mountains and have a precious little granddaughter who has stolen their hearts. As an influencer, Sheila has collaborated with brands like Creamette, Kroger, HERSHEY’S, Hamilton Beach, Garafalo Pasta, OXO, Smithfield, Valley Fig Growers, and more.