In a medium bowl, marinated the beef with the seasonings for at least 20 minutes. Set aside.

In a small bowl, combine all the noodle sauce ingredients together.

In a large saucepan, boil the noodles for 5-6 minutes. Then, drain and rinse with cold water.

Cut the noodles with a pair of scissors a couple of times (between 15-20 cm). Stir in the sauce until well combined. Set aside.

Separate the egg yolk and white into two different bowls.

Whisk the egg yolk with a fork. Heat a non-stick pan with low heat. Add a little bit of oil and wipe the excess with a paper towel. Pour the egg yolk and cook until the edges start changing color. Then, flip it. Once it is cooked, remove it from the heat and set aside to cool.

Now cook the egg white just like the egg yolk. Make sure to keep the eye on it to make sure it does not come out brownish. Once it is cooked, remove it from the heat and set aside to cool.

Once they are cooled enough to handle, cut them into thin strips.

In a big saucepan, heat water until boiling. Blanch the spinach for a few seconds. Then, transfer it to an ice bath. Drain and squeeze out the water. Mix the blanched spinach with 1 tsp sesame oil and 1/2 tsp salt.

Start stir-frying the vegetables from light to dark color.

Heat a large non-stick pan in medium-high heat. Add a little bit of oil, then cook the onion until translucent and fragrant. Transfer the cooked onion into a large mixing bowl.

With the same pan, add more oil if necessary. Cook the carrot with a pinch of salt until it softens. Transfer the cooked carrot into the large big mixing bowl.

Add more oil if necessary. Cook the bell peppers with a pinch of salt until it softens. Transfer the cooked bell peppers into the large big mixing bowl.

Add more oil if necessary. Cook the mushrooms with 1/2 tbsp soy sauce until they are cooked. Transfer the cooked mushrooms into the large big mixing bowl.

Add more oil if necessary. Cook the marinated beef until cooked. Transfer the beef into the large big mixing bowl.

Add more oil if necessary. Pour the noodles into the pan. Make sure not to leave out the sauce on the bottom. Stir fry the marinated noodles for 2-3 minutes or until the sauce fully coated the noodles. Transfer the noodles into the large mixing bowl.

Add sesame seeds and sesame oil into the large mixing bowl. Mix all the vegetables, beef, and noodles until they are well combined.

Pour japchae on the serving plates and garnish with thinly sliced egg white, egg yolk, and more toasted sesame seeds.