Preheat your grill or stovetop grill pan over medium-high heat.

In a small bowl, mix the olive oil, garlic powder, onion powder, smoked paprika, salt, and pepper. Rub this mixture all over the flank steak.

Grill the steak for about 5-7 minutes on each side for medium-rare, or until it reaches your desired doneness. Remove from heat and let it rest for 5 minutes.

While the steak is resting, slice the hoagie rolls in half and toast them lightly on the grill or in a toaster.

Slice the steak against the grain into thin strips.

Assemble the sandwiches by placing a generous amount of steak on the bottom half of each hoagie roll. Top with sautéed bell peppers and onions, and sprinkle with provolone cheese.

If desired, drizzle balsamic vinegar over the top before placing the other half of the roll on top.

Serve immediately and enjoy your delicious steak sandwiches!