Season tuna steaks all over with salt and pepper. Combine black and white sesame seeds on a shallow plate, then gently press tuna steaks into seeds to coat them on all sides.
In a medium skillet over medium-high heat, heat oil until hot. Add tuna steaks to the pan and sear 30 seconds to 1 minute per side, depending on desired doneness. Transfer to a cutting board.
Make salad: In a medium bowl, whisk together dressing ingredients. Season with salt and pepper.
In a large bowl, combine all salad ingredients. Add dressing and toss gently. Slice tuna.
Divide salad between plates and top with tuna.
Notes
This was a delicious 15 minute meal. I love quick and healthy recipes. The arugula and pear salad added a lot of flavor. Any protein could be used in place of the tuna.