In a shallow dish, combine black and white sesame seeds.
Dredge tuna in sesame seeds to coat tuna evenly.
Heat a large skillet over medium-high heat with sesame oil. Add tuna steak to the pan and sear for about 60 seconds on each side. Repeat with remaining steaks and set aside. Allow to cool before slicing into ¼-inch thick pieces.
Whisk together dressing ingredients in a medium mixing bowl and set aside.
Cook rice according to package instructions and divide between two serving bowls along with edamame, green onion, avocado, cucumber, mixed greens carrots and radish. Top bowls with seared tuna steaks and serve with dressing on the side.