Add shrimp to buttermilk in a bowl. Let sit for 10 minutes to tenderize.
Mix all Bang Bang Sauce ingredients in a bowl. Set aside.
In another bowl, mix cornstarch, salt, garlic powder, and pepper.
Remove shrimp from buttermilk and dredge in starch mixture.
Heat oil in skillet to 350°F. Fry shrimp in batches for 1.5 minutes per side.
Transfer to paper towel or rack to drain excess oil.
In a large bowl, toss fried shrimp with Bang Bang sauce.
Garnish with green onions and serve hot.
