Begin by soaking the sweet potato glass noodles in hot water for 30 minutes until they soften and become pliable. Drain the noodles in a colander and set them aside.

In a large non-stick skillet, heat a tablespoon of oil over medium-high heat. Add your choice of sliced beef, chicken, or tofu, and stir-fry for about 5-7 minutes until browned.

In the same skillet, add a little more oil if needed and toss in julienned carrots, bell peppers, and spinach. Stir-fry for about 5-7 minutes until tender but still vibrant.

Once the vegetables are ready, reduce the heat to medium and return the cooked protein to the skillet. Add the soaked sweet potato noodles along with soy sauce, sesame oil, and optional sugar. Toss everything together for about 3-5 minutes.

Transfer your delicious Japchae to a serving platter. Garnish with chopped green onions or chives and serve warm or at room temperature.