Preheat griddle or skillet to medium heat (about 400℉ for griddle cooking).
Add the cubed pork belly to the cooking surface and spread it out in an even layer. Allow the pork belly to cook on the first side for 3-4 minutes, or until it turns golden brown, and then sauté so that the other sides can get crispy. Then, move pork belly to the cooler side of the griddle or, if cooking this recipe in a skillet, remove the crispy pork belly from the pan and set aside. Keep the rendered fat to use for the fried rice.
Spread the leftover pork fat over the cooking surface. Add the white rice and spread it out in a thin even layer so that it can begin frying. After 3-4 minutes, begin to sauté and toss the rice together so that it fries evenly. Then, spread back out in a thin layer.
Immediately after adding the rice to the griddle, start cooking the vegetables. In a separate area on the griddle, add the diced onions and carrots (and/or other vegetables). Sauté until almost tender. *If using a skillet, sauté the vegetables before cooking the rice, and then transfer to a bowl to cook the rice next.
Make a well in the rice. Add 2 tablespoons butter and the minced garlic to the well, so that the butter and garlic are directly on the griddle/skillet. Allow the butter to melt and the garlic to soften and become fragrant. Right before the garlic starts to burn, toss the butter, garlic, and rice together until well combined.
Combine the cooked vegetables and rice together. Then, add the soy sauce, oyster sauce, and mirin. Add the whites of the sliced green onion. Sauté everything together.
Scramble eggs. Once cooked, chop the scrambled eggs up into smaller pieces. Add to the fried rice and toss together.
Right before the fried rice is done cooking, pour on sesame oil and sprinkle on the green parts of the sliced green onion. Stir to combine. When the fried rice is done to your liking, move it to the cooler side of the griddle, or if using a skillet, transfer the rice to a plate.
Prepare the pork belly sauce. Add all pork belly sauce ingredients to a small bowl, and mix well.
Add the crispy pork belly back to the hot cooking surface. Pour the prepared sauce on top and stir together. *I also added a few tablespoons of water to help slow down the reduction process.
After the sauce has reduced a bit and is coating the pork belly, add the fried rice and pork belly together. Toss to combine.
Transfer pork belly fried rice to a serving dish. Garnish with sliced green onions, sesame seeds, etc. and serve hot. *You can also serve your fried rice with Yum Yum sauce and/or Siracha hot sauce.