Soak 1 serving of glass noodles in a bowl of water, covering the noodles completely. They usually come in separate serving sizes, rolled into a ball of some sort.
Heat 1 teaspoon of vegetable oil in a frying pan over low heat. Meanwhile, mince two cloves of garlic.
When the frying pan is hot enough, throw in the minced garlic and fry. Meanwhile, rinse 4 medium shiitake mushrooms and slice it. Check the garlic periodically and make sure it doesn't burn.
When the garlic starts to brown, add the sliced shiitake mushrooms and fry on medium heat. Meanwhile, wash about 1 cup of spinach and chop (if necessary) roughly.
When the shiitake mushrooms are cooked, add in the spinach. Fry until the spinach is cooked.
Add a teaspoon of soy sauce first and mix it thoroughly in the pan.
Next, add the glass noodles and about 2-3 tablespoons of water as the glass noodles need some water to cook properly.
When the glass noodles have cooked (you will be able to tell, usually in about a minute), add in another teaspoon of soy sauce and mix thoroughly.
Turn off the heat and add 1/2 teaspoon of toasted sesame oil. Mix it in and give it a taste. Depending on your soy sauce brand it may/may not be salty enough. Add salt/soy sauce to taste if necessary.