In a bowl, whisk together the mayonnaise, chili garlic sauce, and Sriracha until fully blended. Store covered in the refrigerator for up to two days, or until ready to use.

Place the shrimp in a bowl and pour the buttermilk over them. Marinate for 20 minutes.

In a medium bowl, combine the flour, cornstarch, kosher salt, and black pepper.

Set a cooling rack on top of a sheet pan to hold the breaded shrimp before frying.

Prepare an additional sheet pan lined with paper towels—or with another cooling rack—to hold the fried shrimp.

Preheat the oven to 200°F (93°C).

Drain the shrimp from the buttermilk.

Working in batches, toss the shrimp in the flour mixture until evenly coated.

Shake off excess breading and place the shrimp on the cooling rack so the coating can dry slightly while you heat the oil.

Add the vegetable oil to a large Dutch oven or deep, heavy pot.

Insert a deep-fry thermometer; heat the oil over medium-high until it reaches 350°F (177°C).

This will take approximately 20 minutes.

Add a handful of shrimp to the hot oil. After about one minute, use a slotted spoon to stir and separate the shrimp to prevent sticking.

Fry for 4 to 4 1/2 minutes, or until the shrimp are golden brown.

Transfer the shrimp to the prepared draining station and place in the warm oven.

Continue frying the remaining shrimp in batches, allowing the oil to return to 350°F between batches.

Once all shrimp have been fried, place them in a large bowl and toss with 1 cup of the bang bang sauce.

Reserve remaining sauce for serving.

Place a portion of shredded cabbage in each warmed tortilla.

Top with sauced shrimp, then garnish with radishes, jalapeños, green onions, and cilantro.

Drizzle with additional bang bang sauce, if desired.

Serve immediately for best texture.