Start by slicing the chicken breasts in half horizontally to create thinner cutlets. I like pounding them lightly so they cook evenly and fit perfectly inside the buns. Pat the chicken dry with paper towels before seasoning.
In a large bowl, combine the flour, chili powder, cayenne pepper, garlic powder, salt, and black pepper. Mixing the spices directly into the flour ensures every bite of chicken is flavorful and spicy. This seasoned flour creates the crispy outer layer.
In another bowl, whisk together buttermilk, sriracha sauce, and eggs until smooth. The buttermilk tenderizes the chicken beautifully while the sriracha adds heat and tanginess. This mixture also helps the breading stick properly.
Dip each chicken piece into the flour mixture first, then into the wet mixture, and finally back into the flour again.
Heat vegetable oil in a deep skillet over medium heat until hot. Carefully place the chicken into the oil and fry for about 4–5 minutes per side until golden brown and crispy. Avoid overcrowding the pan because it lowers the oil temperature.
Transfer the fried chicken onto a wire rack or paper towel-lined plate. Letting the chicken rest for a couple of minutes keeps the coating crisp while removing excess oil. The chicken should reach an internal temperature of 165°F before serving.
Lightly toast the brioche buns or potato rolls in a dry skillet or oven. Toasting prevents the buns from becoming soggy and adds a subtle buttery flavor. Warm buns also make the sandwich feel more restaurant-style.
Spread spicy mayo on the bottom bun, then add lettuce, tomato slices, crispy chicken, and pickles. Top with the other half of the bun and gently press everything together. Serve immediately while the chicken is still hot and crunchy.