1. Prepare the marinade for the tuna by whisking together soy sauce, sesame oil, garlic powder, salt and pepper. Place tuna steaks in a Ziploc bag and pour in marinade. Coat well and place in your refrigerator.
2. While tuna is marinating, prepare wasabi mayo by whisking ingredients together in a small bowl. Cover and refrigerate.
3. Prepare fried wontons by heating vegetable oil in a large heavy pot or skillet with high sides over medium high heat (2 inches deep) until it reaches 350 degrees F, using a deep-fry thermometer.
4. Add wontons to oil and fry, working in batches, until chips are slightly puffy and golden brown, stirring gently (about 1 minute). Adjust heat as necessary to maintain a temperature of 350 degrees F. Transfer to a large plate or baking sheet lined with paper towels.

Sear the tuna:

1. Heat a nonstick skillet over medium high heat until hot. Remove tuna steaks from marinade and sear for 1 minute on each side, or until desired temperature is met (my tuna steaks were 1 1/2 inches thick and seared 1 minute on each side to yield rare).
2. Remove tuna steaks from pan and thinly slice into approximately 1-inch pieces.

Prepare the nachos:

1. Assemble nachos by evenly distributing fried wontons onto 2 plates. Top each with 1/2 of the seaweed salad, followed by the sliced tuna, avocado, tomatoes and sesame seeds.
2. Drizzle with desired amount of wasabi mayo and sriracha. Serve with additional soy sauce, if desired.