01 - Combine the beef slices with soy sauce, mirin, sesame oil, and cornstarch in a bowl. Let marinate for at least 15 minutes at room temperature.
02 - Bring a pot of water to a gentle boil. Carefully lower the eggs into the water and simmer for exactly 6½ minutes. Immediately transfer to an ice bath to stop cooking, peel carefully, and set aside.
03 - Heat vegetable oil in a large saucepan over medium heat. Add minced garlic and grated ginger; sauté for 1 minute until fragrant. Stir in chili paste and miso paste, cooking for another minute to develop flavors.
04 - Pour in the stock, soy sauce, rice vinegar, and brown sugar. Bring to a gentle simmer and cook for 10 minutes, allowing the flavors to meld together.
05 - Prepare ramen noodles according to package instructions. Drain well and set aside, tossing with a small amount of oil to prevent sticking if needed.
06 - Heat a separate pan over high heat. Quickly sear the marinated beef for 2–3 minutes until just cooked through. Remove from heat immediately to prevent overcooking.
07 - Add sliced shiitake mushrooms and julienned carrots to the simmering broth. Cook for 3 minutes until just tender-crisp.
08 - Divide cooked noodles among four serving bowls. Ladle the hot broth and vegetables over the noodles. Arrange seared beef slices, halved soft-boiled eggs, baby spinach, spring onions, sliced chili, sesame seeds, and nori strips on top.
09 - Serve the ramen piping hot while the broth is at its peak temperature. For extra richness, drizzle with chili oil just before serving.