- 1 pound flank steak
- ¼ cup + 2 tablespoons olive oil
- Salt and freshly ground black pepper, to taste
- 1 medium red onion, thinly sliced
- ½ cup apple cider vinegar
- 8 slices Italian bread or 4 country rolls, split in half
- ½ cup mayonnaise
- ¼ cup prepared horseradish
- 2 cups arugula, lightly packed
1. Rub the steak with ¼ cup oil and season with salt and pepper. Rub salt and pepper in very well. Put the steak into a sealed bag or plastic container and let it rest in the refrigerator for at least 1 and up to 24 hours. The longer the meat marinates, the deeper the flavor of the final dish.
2. Preheat a grill pan over medium-high heat. Grill the meat on each side until it is cooked to preferred doneness. Check internal temperature with a thermometer. For rare, the temperature should be 125°F.; for medium, the thermometer should register 145°F.; and for well-done, the steak should be cooked to 160°F Remove from heat and let the meat rest for 10 minutes.
3. Slice meat against the grain at a 45-degree angle. If you cut the meat with the grain or at no angle, the meat will be stringy and tough.
4. In a medium sauté pan, heat 1 tablespoon oil until it shimmers. Cook the onion with salt and pepper in the hot oil for 5 to 7 minutes on medium heat. Add vinegar, bring to a boil, and turn off heat. Let pickle for 10 minutes. Strain and cool.
5. Brush the bread with remaining tablespoon oil and grill until golden brown.
6. To make the aioli, combine the mayonnaise, horseradish, and salt and pepper, and mix well. Evenly spread the aioli on 4 slices of bread, top with steak, then onion, and then the arugula. Top with other slices of bread and serve.
TIP: Any meat needs to rest after it has been cooked to retain its juices. If the meat is cut just after being cooked, the juices will run all over your cutting board, and the meat will be dry.