First grill or poach the fish, then put set aside to cool. (This can be done well ahead!)
Finely chop the spring onions and ginger.
Heat the oil in a wok then stir-fry the spring onion and ginger for 3 minutes.
Cut the green beans into small pieces, then add to the wok. Add the soy sauce and the vinegar. Stir-fry for another 2 minutes, then add the rice and a drop of water.
Stir for a couple of minutes, then pull the rice & veggies to one side in the wok. Add a drop of oil and the egg.
Let the egg cook a bit, then mix it well with the rice. If you prefer the egg chunkier, allow it to set, then break it up with the wooden spoon and mix with the rice.
Flake the fish and gently fold in the rice. Let the fish pieces warm through for a couple of minutes.
Add the sesame oil and chopped herbs, stir for a few seconds, then serve with the sesame seeds scattered on top.