1. Preparation
Soak 100g of sweet potato noodles (dangmyeon) in warm water for about 30 minutes until softened.
Prepare the vegetables: thinly slice 1 medium carrot, 1 bell pepper, and 1 small onion.
Chop 100g of spinach and mince 2 cloves of garlic.
If using beef, slice 100g of beef into thin strips against the grain and marinate it with 1 tablespoon of soy sauce, 1 teaspoon of sesame oil, and a pinch of black pepper.
2. Cooking
In a large pan or wok, heat 2 tablespoons of vegetable oil over medium heat.
Add the marinated beef and stir-fry for about 3-4 minutes until browned. Remove and set aside.
In the same pan, add another tablespoon of oil if necessary and stir-fry the minced garlic for about 30 seconds until fragrant.
Add the sliced carrot, onion, and bell pepper, and stir-fry for 4-5 minutes until they are tender-crisp.
Add the chopped spinach and stir-fry until wilted, about 1-2 minutes.
Drain the soaked sweet potato noodles and add them to the pan.
Pour in 2 tablespoons of soy sauce and 1 tablespoon of sugar, and mix everything well.
Return the cooked beef to the pan and add 1 teaspoon of sesame oil. Stir everything together for an additional 2-3 minutes to combine the flavors.
Taste and adjust the seasoning if necessary, then serve hot.