Place flour, cornstarch, panko, garlic powder, onion powder, salt, and pepper onto a large shallow plate, then stir to combine. Set aside.
Place shrimp into a medium sized bowl, cover with buttermilk, then let shrimp marinate for 5 minutes.
Drain the shrimp, then working with one at a time, press the shrimp into the breading until it’s fully coated. Repeat with remaining shrimp.
Heat oil to 375 degrees F in a deep-fryer or large saucepan, then working in batches, submerge the shrimp and fry for 1-5 minutes (depending on size of shrimp) or until cooked through and golden brown.
Use a metal slotted spoon to remove the shrimp, then let drain in a single layer on paper towels while the remaining shrimp cooks.
Once all the shrimp has been cooked and drained, toss in as much or as little bang bang sauce as you’d like, garnish with green onions and sesame seeds, then serve immediately.
*Make the sauce before you start this recipe. You probably won’t use an entire batch of the sauce. Start with a few spoonfuls and add more until the shrimp has been sauced to your liking.Nutrition information uses the entire batch of bang bang sauce, but does not include the canola oil, for frying.