Season the fish with a bit of salt. Place the sesame seeds on a plate and roll the ahi in sesame seeds to coat.

Heat a medium pan over high heat. When the pan is hot, add a tablespoon of avocado oil. Add the sesame covered fish and sear both sides briefly, about 30 seconds a side, leaving the center as rare as possible but browning the sesame crust. Set aside to cool.

Add the avocado oil and shaved root vegetables to a small pot and heat over medium heat, stirring occasionally with a fork to ensure even cooking. The celery root will begin bubbling and will simmer slowly in the oil. When the amount of bubbling reduces and the vegetables are a straw color, begin stirring more often and cook until just golden brown around the edges. Remove the pot from the heat. Transfer the fried vegetables from the oil to a paper towel to drain excess oil. Sprinkle with a bit of salt and set aside. (Use a light color pot so that you can easily see the color of the celery root as it cooks. This can be made up to a week ahead of time and stored in an airtight container.

Whisk together all ingredients except the oil until smooth. Slowly whisk in the oil to emulsify and set aside.

Combine all salad ingredients. Toss with half the reserved dressing. Divide between serving plates. Slice the tuna and lay atop the salad. Drizzle with the remaining dressing and top with vegetable crisps.