- Combine tamari, ginger, mirin and sesame oil in a small bowl. Set aside.
- Place black and white sesame seeds onto a plate and mix together. Coat all sides of tuna fillet with seeds.
- Heat 1-2 tsp sesame oil in a frying pan over medium-high heat. Carefully place tuna into pan and cook for 30 secs on each side, or until seared on the outside but still pink in the middle.
- Remove from pan and allow to rest for 10 mins before slicing.
- To serve, place mixed lettuce in a bowl or plate. Arrange cucumber ribbons, radish slices, edamame beans, sliced avocado and sliced seared tuna over. Garnish with spring onion and serve with dressing.