Heat a large wok or skillet over medium-high heat. Add 1 tablespoon of oil, then brown the ground beef, breaking it apart as it cooks. Season with salt and pepper. Drain excess fat and set aside.
In the same pan, add remaining oil and sauté the garlic for about 30 seconds until fragrant.
Push everything to the side and scramble the eggs in the center of the pan until just set.
Add the frozen peas and carrots, stirring everything together and cooking for 2 minutes.
Add the day-old rice, breaking up any clumps. Stir-fry for 3–4 minutes.
Return the beef to the pan. Pour in soy sauce, oyster sauce, and sesame oil. Toss everything together until well coated and heated through.
Top with green onions and serve hot.