Finely dice the pork belly and slice the green onion, separating the white and green parts.
Heat a large cast-iron skillet over medium-high heat and add the diced pork belly, cooking until the fat renders and the pieces are golden and crispy.
Add the lean ground pork to the skillet, breaking it up with a wooden spoon until browned and fully cooked.
Stir in the minced garlic and the white parts of the green onion, sautéing for about 1 minute until fragrant.
Add the chopped kimchi and gochugaru to the pan, stirring frequently for 2 minutes to caramelize the kimchi slightly.
Add the cooked brown rice, coconut aminos, sea salt, and black pepper, tossing everything together until the rice is evenly coated and heated through.
Push the rice mixture to one side of the pan and drizzle the toasted sesame oil into the empty space.
Crack the egg into the oil and fry until the whites are set but the yolk remains runny.
Transfer the fried rice to a bowl, top with the fried egg, and garnish with the sliced green onion tops.