1. In separate bowls, season the chicken and shrimp and marinate in half the soy sauce and all of the sake for 20 minutes. 2. In a large bowl, lightly beat the eggs and stir in the mirin, the remaining soy sauce and dashi and season. Strain through a fine sieve. 3. Portion the chicken and shrimp into eight ovenproof ramekins and cover with the egg mixtureup until ¾ of the container. 4. Set the oven on steam at 85°C. 5. Seal the ramekins with foil and steam for 15 minutes. 6. Sprinkle the green onion over each of the portions, cover again with foil and allow to rest for another 3 minutes. 7. Serve.