In a large frying pan or deep skillet, add the oil, coming up about 2 inches on the sides. Heat oil to 375˚F.
In the meantime, place raw shrimp in kefir or buttermilk to coat.
In a separate bowl or plate, combine cornstarch, cayenne, garlic powder, salt, and pepper.
Remove shrimp from liquid; shake off any excess, and coat shrimp in cornstarch mixture.
Add coated shrimp to the hot oil and fry for about 1 to 2 minutes per side, or until golden brown.
Remove shrimp to a paper towel lined plate.
In a mixing bowl stir together the mayonnaise, sweet chili sauce, sriracha, and lime juice.
Transfer shrimp to a serving bowl.
Garnish with parsley and sesame seeds.
Serve with the sauce. You can also drizzle the sauce over the shrimp.