Wipe the fish with damp kitchen paper. Place the fish in a large double layered foil and fold the foil up at each side to make 4 small foil boats.
Pour the ponzu into the fish parcel and top with the ginger. Turn the foil into the middle but do not seal it completely. Steam the fish in a bamboo steamer for 10 - 12 minutes. Steam the English spinach separately for 2 - 3 minutes.
Serve the fish and sauce over the spinach and edaname beans.