To make teriyaki sauce, combine mirin, soy and sugar in a small saucepan. Stir over low heat until sugar has dissolved. Simmer for 5 minutes or until reduced slightly. Cool for 5 minutes.
Blanch beans in boiling, salted water for 2 minutes. Drain and refresh in cold water. Place in a bowl with spinach leaves. Combine sesame seeds, extra soy, extra sugar and vinegar. Pour over beans and spinach and toss well. Set aside.
Brush skinless side of salmon with teriyaki sauce. Heat a non-stick frying pan over medium-high heat. Add salmon, skin-side down, and reduce heat to medium. Cook for 3 minutes or until crisp. Turn, add remaining teriyaki sauce and cook for 1-2 minutes, basting occasionally with sauce. Serve salmon with steamed rice and sesame greens.
Use kitchen tweezers to remove bones from fish fillets.