1. In a bowl, soak the dried sea mustard in water for 10 minutes. After 10 minutes of soaking, the sea mustard will yield about 1 cup.
2. On a chopping board, cut the soaked sea mustard into bite sized pieces and keep aside.
3. In a hot pan, fry the chopped beef, add soup soy sauce, sesame oil, and black pepper. Fry until the beef is almost cooked on medium high heat.
4. Add in the chopped sea mustard and sesame oil, fry it for about 3 minutes on high until the beef is completely cooked.
5. Pour 3 cups of water in the pan. Once it starts to boil, add salt and soup soy sauce. Cook for 5 minutes on medium-high.
6. Add minced garlic and cook for another 5 minutes and then turn off the heat.
7. Serve the beef and sea mustard soup in a bowl, garnished with chopped parsley.
After adding the soup soy sauce, and adjust the taste with salt or soup soy sauce if needed.