Cut the salmon fillet into bite-sized pieces.
In a shallow bowl, mix the all-purpose flour, cornstarch, garlic powder, salt, and black pepper.
In another bowl, beat the egg.
Place the panko breadcrumbs in a third bowl.
Coat each salmon piece first in the flour mixture, then dip in the egg, and finally coat evenly with panko breadcrumbs.
Heat vegetable oil in a deep fryer or large pot to 350°F (175°C).
Deep-fry the salmon bites in batches until golden brown and cooked through, about 3-4 minutes per batch.
Drain the fried salmon bites on paper towels.
In a small bowl, whisk together mayonnaise, sriracha sauce, honey, and rice vinegar to make the bang bang sauce.
Arrange the salmon bites in a neat pile on a small white square plate.
Drizzle the bang bang sauce over the salmon bites.
Garnish with finely chopped green onions and sesame seeds before serving.