Cut the beef into small cubes. Marinate with a little soy sauce, 1 tablespoon oyster sauce, black pepper, and minced garlic. Mix well, then set aside a small portion of the beef for the soup. Cut the tomatoes into wedges, reserving a few pieces for the soup. Cut the potato into chunks and lightly fry. Sauté garlic until fragrant, add the tomatoes, season to taste, and add a little water. Bring to a boil.

When the tomatoes are soft, add the fried potatoes and diced asparagus. Let it simmer for a few minutes, then add the onion, green onions, and a little chili and pepper.

Pour 1 bowl of water into a pot and bring to a boil. Add the reserved tomatoes, and when they soften, add the reserved beef for the soup. Season to taste for a flavorful broth, then add the remaining asparagus cut into pieces.

Turn off the heat, add chopped Vietnamese coriander to the soup, and sprinkle with pepper and chili. With this beef, you now have two dishes ready for lunch!