Creating Spicy Korean Gochujang Beef Noodles is simple when you follow these steps:

1. Cook the Noodles: Begin by cooking the noodles according to the package instructions. Drain and set aside.
2. Prepare the Beef: In a bowl, marinate the sliced beef with soy sauce, black pepper, and sugar. Let it sit for about 10 minutes.
3. Heat the Oil: In a large skillet or wok, heat vegetable oil over medium-high heat.
4. Sauté the Vegetables: Add the sliced onion, bell pepper, and broccoli. Stir-fry for 3-4 minutes until they start to soften. Add minced garlic and cook for another minute.
5. Cook the Beef: Push the vegetables to the side of the pan. Add the marinated beef into the skillet. Sauté for 3-5 minutes until the beef is browned and cooked through.
6. Incorporate the Sauce: Stir in gochujang and sesame oil. Mix everything together to coat the beef and vegetables in the sauce.
7. Combine with Noodles: Add the cooked noodles to the skillet. Toss everything together to ensure the noodles are well-coated in the sauce.
8. Garnish and Serve: Remove from heat. Garnish with chopped green onions and sesame seeds if desired.

These straightforward steps will guide you to create a flavorful and satisfying dish that will leave everyone wanting more!