Creating the Korean Steak Sandwich is straightforward if you follow these simple steps:

1. Prepare the Marinade: In a bowl, whisk together soy sauce, gochujang, sesame oil, honey, garlic, ginger, salt, and pepper.
2. Marinate the Steak: Place the flank steak in a resealable bag or shallow dish. Pour the marinade over the steak, ensuring it’s well-coated. Let it marinate for at least 15 minutes or up to 30 minutes for more flavor.
3. Preheat the Grill or Pan: Heat a grill or skillet over medium-high heat.
4. Cook the Steak: Remove the steak from the marinade, allowing excess marinade to drip off. Cook the steak for about 4-5 minutes per side, or until it reaches your desired doneness.
5. Rest the Steak: Once cooked, transfer the steak to a cutting board and let it rest for about 5 minutes.
6. Slice the Steak: After resting, slice the steak against the grain into thin strips.
7. Prepare the Bread: Toast the bread slices lightly if desired to add extra crunch.
8. Assemble the Sandwich: On one slice of bread, spread mayonnaise if using. Layer on the lettuce, sliced steak, cucumber, carrots, and green onions. Top with another slice of bread.
9. Garnish: If desired, sprinkle sesame seeds on the sandwich for added flavor and decoration.
10. Serve: Cut the sandwich in half and serve immediately, enjoying the delicious combination of flavors.

These steps will guide you in creating this incredible sandwich effortlessly.