Step 1: Heat a large wok or a large, heavy-bottomed non-stick pan over high heat until it's smoking slightly. Add 1 tablespoon of cooking oil. Swirl to coat the pan.
Step 2: Add your chosen protein. If using eggs, scramble them lightly in a separate small pan or push the protein to one side, add a little more oil, and scramble 2 eggs directly in the wok, breaking them into small pieces. Remove cooked protein/eggs and set aside.
Step 3: Add another tablespoon of oil to the wok. Add minced garlic and grated ginger. Stir-fry for about 30 seconds until fragrant. Be careful not to burn them.
Step 4: Add the chopped carrots, frozen peas and corn, and bell pepper to the wok. Stir-fry for 2-3 minutes until they start to tenderize but are still crisp.
Step 5: Add the day-old chilled rice to the wok. Break up any clumps with your spatula. Stir-fry for 3-5 minutes, pressing the rice against the hot surface to encourage drying and slight crisping.
Step 6: Push the rice and vegetables to one side of the wok. Add 1 tablespoon of oil to the cleared space. Pour in the soy sauce and oyster sauce (if using) into the hot oil. Let it sizzle for 10-15 seconds before mixing it into the rice. Stir in the reserved protein and eggs.
Step 7: Add the white and light green parts of the sliced green onions and the toasted sesame oil. Toss everything together for another minute, ensuring all ingredients are well combined and heated through. Taste and adjust seasoning with more soy sauce or a pinch of salt if needed. Garnish with remaining green onion tops before serving.