Preheat your grill pan or outdoor grill over medium-high heat.
In a mixing bowl, combine sliced beef, soy sauce, gochujang, sugar, and sesame oil. Let marinate for 10 minutes.
While the beef is marinating, bring a large pot of water to a boil. Cook the instant ramen noodles according to the package instructions. Drain and set aside.
Grill the marinated beef for about 3-4 minutes on each side or until browned and cooked through. Remove from the grill and let rest.
In the same pot, add the beef broth and rice vinegar, and bring to a simmer. Adjust seasoning with salt and pepper as desired.
Stir in the cornstarch slurry to thicken the broth, then add the heavy cream, mixing well until fully combined.
Add the cooked ramen noodles to the pot, gently mixing to coat them in the creamy sauce.
Serve the ramen in bowls, topped with grilled beef, chopped green onions, and sesame seeds. Add a halved boiled egg on top, if desired.