Prepare the shells (Frying method): Heat 2 inches of oil in a deep skillet to 350°F (175°C). Drop a wonton wrapper into the oil and immediately use metal tongs to fold it in half, holding the edges apart to form a taco shape. Fry for 10-15 seconds until golden and crispy. Drain on a wire rack or paper towels. Repeat for all wrappers.

Using a very sharp knife, finely dice the cold sushi-grade Ahi tuna into 1/4-inch to 1/3-inch uniform cubes. Place in a medium bowl.

In a small bowl, whisk together the soy sauce, toasted sesame oil, rice vinegar, grated ginger, and sriracha.

Pour the marinade over the diced tuna. Add half of the sliced green onions and half of the sesame seeds. Gently toss to combine and coat the fish evenly. Do not let it sit in the marinade for more than 10 minutes.

To assemble, place a slice or two of avocado into each crispy wonton shell. Spoon the marinated tuna tartare generously on top of the avocado.

Garnish the tacos with the remaining green onions, sesame seeds, and optional red onion slivers.

Serve immediately to ensure the wonton shells remain perfectly crispy.