In a small bowl add the mayonnaise, Thai sweet chili sauce, and Sriracha and stir.
In a second bowl add the shrimp and buttermilk and stir to coat all the shrimp. Let soak for several minutes.
Remove from the buttermilk and let excess liquid drain away.
Coat the shrimp in cornstarch.
In a heavy-bottomed pan add 2-3 inches of vegetable oil and heat to 375 degrees.
Fry the shrimp until lightly brown, 1-2 minutes on each side. Rest shrimp on wire rack in between batches.
Once fried coat with the sauce and serve immediately.
