Chop the kimchi into bite-sized pieces and reserve two tablespoons of the kimchi juice. Dice the onion, mince the garlic, and slice the green onions. Break apart the cold, day-old rice with your hands or a fork so the grains separate easily during stir-frying. Having all the ingredients ready before cooking ensures the process goes smoothly since fried rice cooks very quickly.

Heat the vegetable oil in a large skillet or wok over medium-high heat. Add the chopped bacon and cook until crispy. Stir in the diced onion and cook until softened, about 3–4 minutes. Add the minced garlic and cook for another 30 seconds until fragrant. If making a vegetarian version, simply skip the bacon and start with the onions in the oil.

Add the chopped kimchi to the skillet and cook for about 3–4 minutes. Stir frequently so the kimchi softens slightly and its flavors deepen. Mix in the kimchi juice, soy sauce, sugar, and gochujang if using. The sauce should become glossy and aromatic as it coats the vegetables.

Add the cooked rice to the skillet and use a spatula to break apart any remaining clumps. Stir continuously so every grain becomes coated with the flavorful kimchi mixture. Continue cooking for about 4–5 minutes until the rice is heated through and slightly toasted in places.

Drizzle the sesame oil over the rice and stir well. Add most of the sliced green onions and mix everything together. Taste the fried rice and adjust the seasoning with additional soy sauce or black pepper if needed. Cook for another minute before removing the skillet from the heat.

In a separate nonstick skillet, fry the eggs until the whites are set and the yolks remain slightly runny, or cook them to your preferred doneness. Divide the kimchi fried rice among serving bowls and top each portion with a fried egg. Sprinkle with the remaining green onions and toasted sesame seeds for extra flavor and crunch. Serve immediately while hot and enjoy every spicy, savory bite.