Slice the pork tenderloin into small cubes and finely dice the pork belly for even rendering.
Heat a large skillet or wok over medium-high heat and add the pork belly, cooking until the fat renders and the pieces become golden and crispy.
Add the pork tenderloin to the skillet, searing until browned on all sides and cooked through.
Stir in the minced garlic and grated ginger, sautéing for 30 seconds until fragrant.
Add the chopped kimchi and sauté for 2 minutes to caramelize the edges and deepen the flavor.
Incorporate the chilled brown rice, breaking up any clumps, and stir-fry for 3 minutes until the rice is heated through and slightly toasted.
Pour in the tamari, kimchi juice, and toasted sesame oil, tossing everything together until the rice is evenly coated and vibrant.
In a separate small non-stick pan, fry the egg until the whites are set but the yolk remains runny for a rich sauce.
Divide the rice into a bowl, top with the fried egg, and garnish with sliced green onions and sesame seeds.