Heat a large cast-iron skillet or wok over medium-high heat.
Add the diced pork belly first, rendering the fat until the pieces are crispy and golden.
Add the diced pork loin to the skillet, seasoning with sea salt and black pepper, and sauté until browned.
Stir in the minced garlic, grated ginger, and the white parts of the scallions, cooking until fragrant.
Add the chopped kimchi and gochujang, stirring constantly for 2 minutes to develop a deep, savory base.
Incorporate the chilled brown rice and tamari, pressing the rice into the pan to let it crisp slightly for 3-4 minutes.
In a separate small non-stick pan, fry the egg with the toasted sesame oil until the whites are set but the yolk remains runny.
Divide the fried rice into a bowl, top with the glistening fried egg, and garnish with the remaining scallion greens.