Preparation: Begin by preheating your oven to 400°F (205°C) and line a baking sheet with parchment paper to ensure an easy cleanup process.

Marinade Creation: In a bowl, whisk together the soy sauce, brown sugar, minced garlic, grated ginger, sesame oil, rice vinegar, and black pepper. For those who enjoy a bit of spice, add in the optional red pepper flakes.

Marinate the Beef: Place the thinly sliced ribeye in the marinade, ensuring each piece is thoroughly coated. Allow it to marinate for about 15 minutes to soak up all the flavors. Meanwhile, slice your onion.

Arrange on Baking Sheet: Spread the marinated beef in a single layer on the prepared sheet, avoiding overcrowding. Evenly distribute the sliced onion over the beef.

Bake: Cook in the preheated oven for 15-20 minutes, or until the beef is caramelized to perfection.

Garnish and Serve: Once done, sprinkle with chopped green onions and sesame seeds for an extra layer of flavor and texture.

Variations & Tips:

Meat Alternatives: While ribeye is preferred for its tenderness, flank steak or thinly sliced sirloin can also work well in this recipe. The key is to slice the meat thinly for optimal texture.

Vegetable Add-Ins: To make the dish more substantial, consider adding thinly sliced carrots or bell peppers to the sheet pan before baking. They'll roast beautifully alongside the beef.

Flexible Marinade Time: Although 15 minutes of marinating is ideal, you can adjust this time based on your schedule. A quick 5-minute marinade can still impart great flavor, but if time allows, marinating for up to an hour will enhance the dish even further.

Creative Leftovers: If you find yourself with leftovers, they can be repurposed into delicious taco fillings or as a flavorful salad topping the following day.

This Easy Sheet Pan Beef Bulgogi brings a world of flavor to your dinner table with minimal effort, making it a fantastic choice for those evenings when time is of the essence but a flavorful meal is a must. Enjoy the culinary journey!