Clean the beef and cut it into 1/2-inch (about 1.5 cm) cubes. Place in a bowl and add 1 tablespoon seasoning powder, 1 tablespoon oyster sauce, 1/2 tablespoon MSG, black pepper, and 1 tablespoon minced garlic. Mix well and marinate for 15 minutes.

While the beef is marinating, clean the onion and bell pepper. Cut them into 1/2-inch (about 1.5 cm) cubes. Heat a pan, add some oil, and sauté minced garlic until fragrant. Add the bell pepper and onion, stir-fry over high heat until just cooked, then transfer to a plate.

Add oil to the pan and sauté minced garlic until fragrant. Add the marinated beef and stir-fry over high heat. Add 2 tablespoons ketchup and stir well. Adjust seasoning to taste. Add the cooked vegetables back in, mix everything together, and transfer to a plate. Garnish with tomato, cucumber, and lettuce. Drizzle a little vinaigrette on top and serve with bread.