Place the miso, tahini, sugar, and water in a saucepan and stir over low heat for 2 minutes or until thickened. Heat a nonstick frying pan over medium to high heat. Add the salmon, skin side down, and cook for 3 minutes or until crisp. Brush the salmon with miso sauce, turn, and cook for 1 minute.
For the fennel salad, combine the fennel, cucumber, lime juice, fish sauce, sugar, and coriander leaves. To serve, place the fennel salad on plates and top with the salmon. Serve with the remaining miso sauce.
Recipe courtesy of Donna Hay's Off the Shelf (Morrow, 2001)