In a bowl, combine the buttermilk, cayenne pepper, paprika, garlic powder, onion powder, salt, and pepper. Add the chicken thighs to the marinade, ensuring they are fully coated. Cover and refrigerate for at least 1 hour (or overnight for best results).

Using a spiralizer or a knife, cut the potatoes into curly shapes. Rinse the cut potatoes in cold water to remove excess starch, then pat dry. In a large bowl, toss the curly potatoes with cornstarch, paprika, garlic powder, cayenne pepper, and salt until evenly coated.

Heat oil in a deep fryer or a large pot to 350°F (175°C). Carefully add the seasoned curly fries in batches, frying until golden and crispy, about 4-5 minutes. Remove with a slotted spoon and drain on paper towels. Season with additional salt while hot.

In a separate bowl, mix the flour with a pinch of salt and pepper. Remove the marinated chicken from the fridge and dredge each piece in the flour mixture, ensuring they are well-coated. Heat oil in a skillet over medium-high heat. Add the chicken thighs and fry for about 6-8 minutes per side, or until golden brown and cooked through. Once cooked, remove from the skillet and let drain on paper towels.

In a small bowl, whisk together mayonnaise, Sriracha sauce, and lime juice until smooth. Adjust the spice level to your preference.

Toast the burger buns lightly if desired. Place a lettuce leaf on the bottom half of each bun, followed by a fried chicken thigh, sliced tomatoes, and pickles. Drizzle some Sriracha mayo on top and cover with the top half of the bun.

On a large platter, arrange the crispy spicy chicken burgers alongside a generous serving of curly fries. Serve with extra Sriracha mayo on the side for dipping.