Heat the vegetable oil in a deep pan or skillet over medium-high heat.
Season the shrimp with salt and pepper.
Dredge the shrimp in the cornstarch, making sure they're evenly coated.
Fry the coated shrimp in batches until they are golden brown and crispy, about 2-3 minutes per side. Place the fried shrimp on a paper towel-lined plate to drain excess oil.
While the shrimp is cooking, dice your tomatoes and slice your green onions.
In a separate bowl, whisk together mayonnaise, sweet chili sauce, rice vinegar, sriracha sauce, and sugar. Taste and adjust the spice level with more sriracha if needed. Set the sauce aside.
In a large bowl, drizzle the crispy shrimp with the prepared Bang Bang Sauce. Toss the shrimp to coat them evenly with the sauce.
Garnish the Bang Bang Shrimp with chopped green onions and tomatoes.
Serve your homemade Bang Bang Shrimp as an appetizer or over a bed of white rice or fresh lettuce.