To make gochujang sauce, combine together gochujang, soy sauce, vinegar or mirin, sugar and water. Set aside.
Cook noodles following packet directions. Drain. Set aside.
Heat oil in a wok over high heat.
Add garlic and spring onions (scallions). Stir fry for a minute or until the spring onions are tender.
Add gochujang sauce. Stir fry for 3 minutes.
Add noodles. Toss to combine.
Drizzle with sesame oil.
Transfer noodles to serving bowls.
Top with boiled egg and bok choy. Sprinkle with sesame seeds.
Garnish with chopped spring onions (scallions).