Begin by warming the olive oil in a large pot over medium-high heat. Add the beef brisket and allow it to brown evenly, stirring occasionally for about 6-8 minutes. Once browned, remove the beef from the pot and set it aside.

In the same pot, toss in the chopped onion, minced garlic, and fresh ginger. Cook until the onion softens and becomes translucent, approximately 4-5 minutes.

Return the browned beef to the pot and add the beef stock, tamari sauce, oyster sauce, ground black pepper, and water. Increase the heat to bring the mixture to a vigorous boil, then lower the heat and let it simmer gently for about 1 hour, or until the beef is fork-tender.

Stir in the rice noodles, shredded napa cabbage, and sliced bell peppers. Allow everything to cook together for another 7-9 minutes, or until the noodles are tender and the vegetables are cooked through.

Adjust the seasoning to your liking, then ladle the soup into bowls. Top each serving with a sprinkle of fresh parsley for a burst of flavor.