1) In a large saucepan, combine the cooked rice with 60 ml of water. Cover and cook until the rice absorbs the water and is cooked through.
2) In a large bowl, combine rice, edamame, carrots, spring onions, coriander, sesame oil and mustard. Stir to combine.
3) Place the tuna fillets on a plate and pour teriyaki sauce on top. Season, to taste, with salt and black pepper.
4) Arrange red lettuce or radicchio leaves on individual plates. Spoon edamame-rice salad over top or inside radicchio leaf. Top each with tuna fillets and serve.