Before starting, preheat your broiler to high.Wash and dry all produce. Core, then cut the pepper into 1/2-inch strips. Halve the rolls. Pat the steak dry with paper towels. Sprinkle half the Italian seasoning (use all of the Italian Seasoning for 4 ppl) all over the steak, then season with salt and pepper. Set aside.

Heat a large non-stick pan over medium-high heat. When hot, add 1 tbsp oil (dbl for 4 ppl), then the onions and peppers. Cook, stirring occasionally, until tender-crisp, 3-4 min. Season with salt and pepper. Transfer to a plate.

Add 1/2 tbsp oil (dbl for 4 ppl), then the steak to the same pan. Sear until golden-brown, 1-2 min per side. (It’s okay if it doesn’t cook all the way through at this step!) Remove the pan from the heat and transfer the steak to a foil-lined baking sheet. Broil in the middle of the oven, until cooked to desired doneness, 4-7 min.**

While the steak finishes cooking, whisk together 1 tbsp balsamic glaze and 1 tbsp oil (dbl both for 4 ppl) in a large bowl. Set aside.

Thinly slice the steak. Remove the foil from the baking sheet, then arrange rolls, cut-side up on the same baking sheet. Divide the mayo between rolls. Top the bottom roll with the steak, then drizzle over remaining balsamic glaze. Add half the onion-pepper mixture over top. Sprinkle the cheese over the veggies. Broil, in the middle of the oven, until cheese melts, 2-3 min. (TIP: Keep an eye on them so that they don't burn!)

Add the spinach and remaining peppers and onions to the large bowl with the dressing. Toss to combine. Season with salt and pepper. Divide Italian sandwiches and spinach-pepper salad between plates.