Begin by cooking the rice, ideally the night before, and store it in the fridge so it has time to harden. Alternatively, you can buy takeout rice or microwave the just cooked rice.
Gather the chicken and marinade ingredients. Cut the chicken into small bite-sized pieces. Season with salt and pepper and set aside.
Prepare the garlic and onion by mincing them. Slice the mushrooms. Then spray a skillet with cooking spray and sauté the vegetables, including the kimchi. Begin to add in the chicken pieces in a single layer. Cook for about 3-4 minutes on each side while stirring the vegetables around consistently to avoid overcooking and burning anything.
Once the chicken looks about done and the vegetables have softened, add in the overnight rice, breaking down the clumps with a wooden spoon. Add in the gochujang, sugar, and soy sauce and mix everything together thoroughly. Use kimchi juice to help dissolve the gochujang and deglaze the skillet. If you don't have any kimchi juice, chicken stock or water can work as well.
Season with salt and black pepper as needed and mix together thoroughly. Remove from heat and set aside.
Fry 1 egg to desired doneness and top on the kimchi fried rice. Garnish with furikake and scallions and enjoy your yummy kimchi fried rice!