Heat a large skillet or wok over medium-high heat and add the diced pork belly.
Cook the pork belly until the fat renders and the pieces become golden and crispy.
Add the minced garlic and the white parts of the sliced green onions, sautéing for 30 seconds until fragrant.
Incorporate the chopped kimchi and gochujang, stirring frequently to combine the flavors with the pork.
Add the cooked brown rice to the skillet, breaking up any large clumps with a spatula to ensure even heating.
Stir-fry the mixture for 3 minutes until the rice is evenly coated in the sauce and heated through.
Push the rice to the outer edges of the pan and pour the egg whites into the center.
Scramble the egg whites until fully cooked and opaque, then fold them back into the rice mixture.
Stir in the tamari, sea salt, and black pepper, then remove the pan from the heat.
In a separate small non-stick pan, fry the whole egg until the edges are crisp but the yolk remains runny.
Divide the rice into bowls and top with the fried egg, the green onion tops, and a drizzle of toasted sesame oil.