Start by patting your ribeye or sirloin steak dry with paper towels to ensure proper searing. In a bowl, mix together soy sauce, gochujang, sesame oil, brown sugar, minced garlic, and ground black pepper until well combined. Add the steak to the mixture, allowing it to marinate for 30 minutes at room temperature or up to 4 hours in the refrigerator for enhanced flavor.

Preheat your grill or a heavy-bottomed pan to medium-high heat, around 375°F. Once hot, place the marinated steak on the grill and cook for approximately 3-5 minutes per side, achieving a perfect medium-rare doneness (130-135°F). After grilling, transfer the steak to a cutting board and let it rest for 5-10 minutes.

In a medium saucepan, bring your choice of chicken or beef broth to a gentle simmer over medium heat. Once simmering, add the instant ramen noodles and let them cook for 2-3 minutes, stirring occasionally until they are al dente.

Stir in gochugaru, additional soy sauce, rice vinegar, and remaining sesame oil into the simmering broth. Allow this mixture to simmer for an additional 1-2 minutes.

To make the creamy sauce, take a small amount of the hot broth and whisk it with mayonnaise in a separate bowl until smooth. In serving bowls, place the drained ramen noodles and ladle the spiced broth over them. Top with the sliced grilled beef and drizzle the creamy sauce generously. Serve immediately while hot.