Cook the rice according to pack instructions. Meanwhile, in a shallow bowl, mix together the miso, mirin and tamari or soy sauce. Pat the cod fillets dry with kitchen paper, then add to the bowl and gently turn until coated; set aside to marinate for 10 minutes. Cook the edamame and green beans in a pan of boiling salted water for 3-5 minutes, then drain.
Heat the oil in a frying pan over a medium-high heat. Cook the cod for 2-3 minutes on each side, until cooked through and opaque. Stir the rice vinegar through the cooked rice and serve with the cod, edamame, green beans and sushi ginger, if liked, scattered with the sesame seeds.
