Mix the wasabi and soy sauce together in a bowl, then marinate the tuna in the mixture for 30 minutes, refrigerated.
Place all ingredients except olive oil in a saucepan and reduce by 1/2. Blend in the olive oil with a whisk to emulsify.
Toss the tuna in sesame seeds. Pan sear the tuna to the desired doneness. Toss field greens in the orange ginger dressing. Arrange the greens on a plate. Slice the tuna and place on the greens.
Recipe courtesy of Chef Lisa Somma, Soho Restaurant, Long Branch, NJ