If using freshly cooked rice, let it cool completely to prevent it from becoming mushy. It's best to use day-old rice for fried rice recipes.
Heat vegetable oil in a large skillet or wok over medium-high heat. Add diced onions, garlic, carrots, bell peppers, and peas. Stir-fry for about 5-7 minutes, until the vegetables are tender.
If you're using cooked chicken or pork, add it to the pan and stir-fry for another 2-3 minutes until heated through. You can also use shrimp or tofu as an alternative.
Push the vegetables and meat to one side of the pan, then crack eggs into the other side. Scramble the eggs until fully cooked, then mix everything together in the pan.
Add the cooled rice to the pan and break up any clumps. Stir everything together, ensuring the rice is mixed well with the vegetables, eggs, and meat.
Pour in soy sauce, oyster sauce, and sesame oil. Stir to coat the rice evenly with the sauces, and season with salt and pepper to taste. Continue to stir-fry for 3-4 more minutes, allowing the rice to absorb the flavors and get slightly crispy.
Stir in green onions for a fresh burst of flavor. Serve immediately and enjoy your delicious Subgum Fried Rice!