Balsamic Flat Iron Steak Sandwich with Grilled Peaches

Instructions

1. The night before:
   Place the steak on a wire cooling rack fitted inside of a baking pan. Season the steak on all sides with Kosher salt. Place in the fridge to age, uncovered, for a minimum of 8 hours and up to 24 hours.
2. The day of:
   Combine the ingredients for the marinade in a small bowl: olive oil, balsamic vinegar, honey, thyme, Dijon, garlic, and pepper. Pour over the steak. Let marinate for 2 hours.
3. Preheat a grill to medium-high heat (425°F). While the grill heats, prepare the balsamic sauce for the peaches.
4. In a small saucepan, combine the balsamic vinegar, honey, butter, thyme, pepper, salt, and red pepper flakes. Bring to a boil over medium heat. Reduce heat to medium-low and simmer vigorously (not a full boil), stirring often, for 4 minutes. Remove from heat.
5. Once the grill is heated, remove the steak from the marinade. Grill for 4-5 minutes on each side or until the internal temperature is 125°F for medium-rare, 135°F for medium, or 145°F for well-done. Let the steak rest for 10 minutes before slicing against the grain into thin strips.
6. While the steak rests, grill the peaches for 2 minutes. Flip and grill for 2 minutes more after brushing the balsamic glaze on the side with grill marks. Remove from grill and transfer to a serving plate.
7. Serve the thinly-sliced steak on a toasted burger bun topped with thinly-sliced havarti, grilled peaches, extra balsamic sauce, fresh basil, and arugula. Enjoy!