Begin by slicing the ribeye or sirloin into thin strips for optimal tenderness. In a mixing bowl, combine the beef with soy sauce, gochujang, sesame oil, brown sugar, minced garlic, and black pepper. Ensure the beef is well-coated with the marinade and let it sit in the refrigerator for at least 30 minutes.

In a small bowl, whisk together mayonnaise, sriracha, sesame oil, garlic powder, and a pinch of sugar to create a luscious creamy sauce. Cover and refrigerate until ready to serve.

In a large pot, bring chicken or vegetable broth to a gentle simmer. Stir in gochugaru, soy sauce, rice vinegar, sesame oil, and a pinch of salt. Add the ramen noodles and cook according to package instructions until al dente.

Preheat a grill pan over high heat. Add the marinated beef strips, searing for 2-3 minutes on each side. Remove from heat and slice into bite-sized pieces.

Divide the cooked ramen and broth among large bowls. Top each bowl with grilled beef slices and drizzle with creamy sauce. Garnish with green onions, sesame seeds, and chili oil.