In a mixing bowl, combine mayonnaise, sriracha, sesame oil, soy sauce, and fresh lime juice. Stir until smooth and creamy, then gently fold in diced sushi-grade tuna, red onion, green onion, and toasted sesame seeds. Cover tightly with plastic wrap and refrigerate for at least 30 minutes.

Heat oil in a skillet over medium heat, aiming for about 350°F for optimal frying. Carefully add wonton wrappers, one at a time, shaping them into taco shells using tongs. Fry each shell for about 1-2 minutes on each side until golden and crispy, then remove and place on paper towels to drain excess oil.

Once the wonton shells have cooled slightly, spoon the chilled tuna mixture generously into each taco shell. Add slices of fresh avocado on top and sprinkle with extra green onion if desired. Include optional toppings like jalapeño or pickled ginger to personalize the tacos.

Serve these tacos immediately while shells are still warm and crispy. Arrange on a platter for presentation and enjoy the burst of flavors.