Heat 1.5 tbsp sesame oil in a wok or large skillet over high heat until shimmering. Pour in beaten eggs and scramble until cooked through and slightly browned, about 2 minutes. Transfer to a plate and set aside.
Add remaining 1.5 tbsp sesame oil to the pan. Add minced garlic, minced ginger, and diced onion, stirring constantly for about 1 minute until fragrant and softened. Do not burn.
Add diced cooked prime rib to the pan and stir-fry for 2-3 minutes until the edges are slightly crispy and the meat is heated through. This caramelization is key for flavor.
Add the white parts of the green onions and stir for 30 seconds. Add frozen peas and carrots and cook for another minute until heated through.
Add cooked rice to the pan, breaking up any clumps with a spatula or wooden spoon. Stir constantly for 3-4 minutes, working quickly to heat the rice and incorporate the other ingredients. The goal is to coat all rice grains with oil and heat them evenly.
Pour in soy sauce, oyster sauce, and beef broth or prime rib au jus, stirring constantly for 1 minute. The rice should be moist but not wet. Add the scrambled eggs back to the pan and toss everything together for another 1-2 minutes.
Drizzle in rice vinegar and season with white pepper and sea salt. Add butter to finish and stir gently. Remove from heat and immediately add green parts of the green onions and roasted cashews or peanuts if using.
Divide among serving bowls and garnish with sesame seeds. Serve immediately while hot and crispy. Pair with additional soy sauce on the side for dipping.
4 servings