In a medium bowl, combine the sliced beef with 1 tablespoon soy sauce and sesame oil. Let it marinate for at least 15 minutes while you prepare the other ingredients.

Heat 1 tablespoon of vegetable oil in a large pan or wok over medium-high heat. Add the marinated beef and stir-fry until fully cooked and browned, about 3-4 minutes. Remove the beef from the pan and set aside.

In the same pan, add another tablespoon of vegetable oil. Add the finely chopped onion, minced garlic, and grated ginger. Stir-fry until the onion becomes translucent and fragrant, about 3 minutes.

Push the onion mixture to the side of the pan and pour in the beaten eggs. Allow the eggs to cook slightly for a few seconds, then scramble and mix with the onion mixture.

Add the cooked rice, breaking up any clumps with a spatula or spoon. Stir-fry the rice for about 3 minutes, ensuring it is evenly coated with the onion-egg mixture.

Add the remaining soy sauce, oyster sauce, frozen peas, and carrots. Stir all ingredients well, cooking until the peas and carrots are heated through, about 2 minutes.

Return the cooked beef to the pan, mixing well with the rice. Add the sliced green onions, and stir everything together to combine flavors.

Taste and season with salt, pepper, and optional fish sauce if desired, adjusting the seasonings to your liking. Serve hot, garnished with additional green onions if preferred.