1.In a medium bowl combine beef, 1 tablespoon soy sauce, 1 tablespoon sugar, 1 1/2 teaspoon sesame oil, mirin, and garlic. Let marinate while preparing other ingredients.
2.Heat a large skillet over medium-low heat. Add 1 teaspoon vegetable oil; swirl to coat. Add beaten eggs swirl skillet until egg covers surface in a thin layer. Cook until it’s just set, about 2 to 3 minutes, then flip over and cook for another minute. Slip omelet onto a plate and let it cool. Slice cooled egg omelet into thin ribbons and transfer to large serving dish.
3.Heat the same skillet over medium-high heat. Add 1 teaspoon vegetable oil and sliced onion. Season with a pinch of salt, sauté 4 to 5 minutes. Remove onion from pan into serving dish.
4.Add 1 teaspoon oil to the pan and red pepper with a pinch of salt. Sauté 1 minute, transfer to serving dish. Add 1 teaspoon oil to the pan, add carrots and a pinch of salt. Sauté 3 minutes, transfer to serving dish. Add mushrooms, sauté 3 minutes, transfer to serving dish. Add green onions to serving dish.
5.Add 1 teaspoon oil and add marinated beef to the pan; sauté for 2 to 5 minutes or until beef is cooked through and all moisture has evaporated, transfer to serving dish.
6.Bring a large pot of water to a boil. Add generous amount of salt. Add the spinach, cook 10 seconds. Move spinach from the boiling water to ice water immediately. Squeeze out water from spinach gently, transfer to serving dish.
7.In the same water, cook the Korean sweet potato noodles. Boil noodles according to package directions for 6 to 10 minutes. Drain the cooked noodles and place in the serving dish. Cut the noodles as needed.
8.In a small bowl, mix together 1/3 cup soy sauce, honey, 2 tablespoons sesame oil, sesame seeds, and black pepper, set aside.
9.Pour 2/3 of the sauce into the noodles section and gently mix until noodles absorbed all of the sauce. Mix the noodles and all of the ingredients together. Add the rest of the sauce toss gently to combine everything. Garnish with additional sesame seeds, as desired. Serve immediately.