1. In a bowl stir together the miso, mirin, and sake (if using). Pour marinade into the base of a small metal or plastic container. Place the salmon fillets flesh side down into the miso marinade. Sprinkle small amount of salt on the salmon skin, cover and leave in the fridge for at least 30 mins (1 hour is better).
2. Heat frying pan and lightly spray with olive oil. Pat salmon skin dry with paper towel and wipe off excess marinade.
3. Place skin side down into hot frying pan and press lightly for approximately 30-40 seconds, allowing skin to go crisp. Using tongs turn salmon over and cook until marinade starts to caramelise, turn on its side and repeat for both. Remove from pan and set aside to rest.
4. Meanwhile, make the cucumber salad. Using a vegetable peeler, shave the cucumber into long, thin ribbons, alternatively cut cucumber in half lengthways and slice on an angle.
5. Whisk together the rice wine vinegar, oil and honey. Toss the cucumber ribbons in the dressing with chopped mint and dill, then curl them up on two plates.
6. Serve with the salmon and some plain white rice sprinkled with toasted sesame seeds.