Smear wasabi onto 1 side of tuna and then coat with the sesame seeds. Press the seeds into the tuna with your hands or with the back of a spoon. Repeat on the other side.
Melt oil in a pan over high heat. Once it’s heated place tuna in and sear it for about 2 minutes. Use a metal spatula to carefully flip. Sear on the other side for an additional 2 minutes.
Notes
*Ask the seafood manager at your local grocery store for tuna that you can eat rare because while you're searing your tuna, it will still be partially raw in the middle (trust me - it's delicious this way!). I get my tuna frozen.