Make the sauce. In a mixing bowl, combine the mayonnaise, sriracha, and sweet chili sauce. Stir until smooth, then whisk in the soy sauce. Taste and adjust the sriracha-to-sweet-chili-sauce ratio to control the spice level.
Prepare the egg wash. Crack the eggs into a separate bowl and whisk them together. Whisk in the half and half. This mixture stands in for buttermilk.
Season the cornstarch. In a third bowl, add the cornstarch and season it with salt and pepper.
Bread the shrimp. Working with a few shrimp at a time, dip each one in the egg wash, then dredge it in the seasoned cornstarch, making sure it's fully coated.
Chill the shrimp. Place the coated shrimp on a wire rack and let them rest while you heat the oil. This helps the coating set.
Heat the oil. Pour the oil into a heavy-bottomed pot and heat it to 350°F. Use a kitchen thermometer to check the temperature before frying.
Fry the shrimp. Add the shrimp to the hot oil one at a time, without overcrowding the pot. Fry for about 90 seconds per side, until cooked through. Cornstarch gives a lighter color than flour, so don't expect a dark, popcorn-shrimp look; the shrimp will still be crunchy.
Drain and cool. Remove the shrimp with a slotted spoon and place them on a paper towel-lined plate to drain and cool slightly.
Coat in sauce. Add the shrimp to the bowl of bang bang sauce one at a time, using your hands to make sure each piece is fully coated.
Plate and garnish. Arrange the sauced shrimp on a plate and garnish with diced chives or green onion. Serve immediately.