Slice the beef: If not already thin, freeze the beef for 20 minutes, then slice against the grain into thin strips. Pat dry and set aside.

Make the marinade: In a bowl, combine soy sauce, sesame oil, brown sugar, gochujang, rice vinegar, garlic, and ginger. Stir until smooth.

Marinate the beef: Add the beef to the bowl, toss to coat, and let it sit for 15–30 minutes. Longer equals deeper flavor, but even 15 minutes helps.

Prep the broth: In a pot, bring the broth to a gentle simmer. Add 1 tablespoon soy sauce and 1 teaspoon sesame oil. Keep warm over low heat.

Cook noodles: Boil ramen according to package directions until just shy of tender. Drain, rinse briefly under hot water, and set aside.

Sear the beef: Heat a large skillet over medium-high. Add oil, then the marinated beef in a single layer. Cook 1–2 minutes per side until browned and slightly caramelized. Work in batches to avoid steaming.

Sauté the vegetables: In the same pan, add a touch more oil if needed. Toss in onion and mushrooms with a pinch of salt. Cook 3–4 minutes until softened and golden. Add spinach or bok choy and cook just until wilted.

Deglaze (optional but great): Splash a few tablespoons of broth into the hot pan to lift the browned bits. Pour those juices into the main broth pot for extra depth.

Assemble bowls: Divide noodles into bowls. Ladle hot broth over them. Top with beef and vegetables.

Add toppings: Finish with scallions, sesame seeds, and any extras like kimchi, a soft-boiled egg, nori, or a drizzle of chili oil.

Taste and adjust: Add a little soy sauce for salt, rice vinegar for brightness, or gochujang/chili oil for heat.