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