Add shrimp to a large bowl and cover in the buttermilk. Marinate for 20-30 minutes while you prep the oil, coating and sauce.
Heat peanut or vegetable oil in a large pot set over medium heat to 350 degrees. You will need a thermometer. It will take at least 15 mintues for the oil to come to temperature. Once it does, lower the heat to just under medium to maintain 350 degrees.
To another mixing bowl add cornstarch, garlic powder, onion powder and kosher salt. Whisk until combined and set aside.
To a skillet add the mayo, sweet Thai chili sauce, honey, rice vinegar and sriracha. Whisk until combined. Leave the heat off for now.
Remove shrimp, shaking off excess buttermilk and toss in the cornstarch mixture. Coat all over, remove from the bowl and lay on a foil or parchment lined sheet pan. Try and keep the shrimp from touching each other.
Begin frying your shrimp in batches of 8 shrimp at a time. Lower each shrimp in one at a time but work quickly. Set a timer for 4 minutes.
Remove shrimp from the oil with a slotted spoon and place in a paper towel lined mixing bowl. Continue cooking the shrimp in batches allowing the oil to get back up to 350 degrees between each batch.
On the last batch of shrimp, turn the heat on to the sauce. Heat the sauce until it's bubbling. Stir and add all the cooked shrimp. Toss in the sauce.
Garnish with green onions on top and serve over white rice with a side of soy sauce. Eat hot and fresh!