In a small bowl, combine gochujang, corn syrup, sugar, vinegar, soy sauce, pineapple juice, and minced garlic. Whisk until smooth and set aside.

Bring a medium pot of water to a rolling boil. Add soybean sprouts and cook for 3-4 minutes until tender. Transfer to ice water, then drain.

Wash and chop vegetables: slice green and red cabbage, cut carrot into matchsticks, and cucumber into strips.

In a large pot, boil water. Add jjolmyeon and cook for about 5 minutes. Drain and rinse under cold water.

In a large bowl, place cooled noodles, then top with soybean sprouts, cabbages, carrot, and cucumber. Drizzle with gochujang sauce or serve on the side. Garnish with hard-boiled egg if desired.