Prepare the thinly sliced beef brisket into bite-sized pieces.
Julienne the onion and green onion.
Layer the onion, green onion, and sliced beef brisket in a pot.
Mix soy sauce, minced garlic, pepper, and water to make a seasoning sauce.
Pour the seasoning sauce and water into the pot and bring to a boil over medium heat.
Finish cooking when the meat and vegetables are cooked through.