Mix the mayonnaise, sweet chili, and Sriracha sauce with a whisk.
Set sauce aside for flavors to infuse.
Taste after 10 minute and then add more Sriracha sauce to increase spiciness.
Dry shrimps with paper towel so the batter can stick better.
Mix the flour, starch, salt, and baking powder.
Bring a skillet of oil to heat.
Pour the soda water into the flour mixture and whisk away. If the batter is too thin you can add flour one tablespoon at a time until you get desired consistency. It will remain transparent when you dip the shrimp, you want it to be light and crunchy.
Dip the shrimp into the batter, and then immediately move it to the oil.
Fry both sides until golden then drain in a colander to get rid of the excess oil.
Toss the fried shrimp into the sauce one batch at a time to ensure even distribution of the sauce.
Garnish with spring onions and serve.