Gather all the ingredients.
Grate ginger with a grinder or a garter and set aside.
In a small mixing bowl, add grated ginger, Sesame Oil, black pepper and salt. Mix well then transfer to a zip lock bag.
Pat dry the ahi steak fillets and then transfer to the zip lock bag, remove any excess air and seal. Marinate in the refrigerator for at least 1 hour and up to 2 hours, flipping once halfway through.
Once marination is complete, mix Wasabi Powder and 1/2 tsp water and to form a paste (add another 1/4 tsp of water if paste is too dry). Once paste is formed, place the small mixing bowl upside down to bring the most out of the flavors. Note – the more you mix the Wasabi Powder, the spicier it will get. If using packet/tube wasabi, skip to next step.
In a small Teflon frying pan, combine Swerve/Monkfruit, Japanese Sake, water, Rice Vinegar, Soy Sauce and bring to boil. Once boiling, reduce heat to simmer and simmer for 1 minute. Next, add wasabi from step 5) and Xanthan Gum, mix well until Xanthan Gum has dissolved, remove from heat and set aside.
Finely chop green onions and set aside.
Remove ahi steaks from marinade, wash off any excess liquid and pat both sides of the tuna steak dry with a paper towel.
In a large Teflon frying pan, add high temp neutral cooking on high heat. Once the oil starts to lightly smoke, about 2-3 minutes, add tuna and sear uncovered for 15-20 seconds on all sides. Note - if you prefer medium-well cooked steaks, sear for 30-45 seconds per side, but we don't recommend cooking it for any longer.
Transfer seared ahi steak to a serving plate, brush glaze sauce on top and finish with a sprinkle of chopped green onions and optional toasted sesame seeds. Enjoy!