01 - In a small bowl, combine dashi stock, soy sauce, mirin, sake, and sugar. Stir until the sugar dissolves completely.
02 - Heat a medium skillet over medium heat. Add the sliced onion and sauce mixture. Simmer for 3–4 minutes until the onion softens and becomes translucent.
03 - Add the chicken pieces to the pan. Cover and simmer for 6–8 minutes, turning halfway through, until the chicken is cooked through and no longer pink in the center.
04 - Lightly beat the eggs in a bowl. Pour eggs evenly over the chicken and onion mixture. Cover and cook for 1–2 minutes until the eggs are just set but still slightly runny. Remove from heat immediately to prevent overcooking.
05 - Divide the hot rice between two bowls. Gently slide the chicken and egg mixture over the rice, ensuring the sauce is distributed evenly.
06 - Sprinkle sliced spring onions over the top. Serve immediately while the eggs are still creamy and the rice is hot.