01 - Combine dashi stock, soy sauce, mirin, sake, and sugar in a small bowl. Stir vigorously until sugar completely dissolves.
02 - Heat a medium skillet over medium heat. Add sliced onion and prepared sauce mixture. Simmer uncovered for 3–4 minutes until onions become translucent and tender.
03 - Add chicken pieces to the pan. Cover and simmer for 6–8 minutes, turning pieces halfway through cooking, until chicken is fully cooked through and no longer pink in the center.
04 - Lightly beat eggs in a bowl until just combined. Pour eggs evenly over the chicken and onion mixture. Cover and cook for 1–2 minutes until eggs are barely 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 - Top with sliced spring onions. Serve immediately while eggs remain silky and rice is hot.