In a medium bowl, whisk together the buttermilk, salt, pepper, and optional hot sauce. Add the chicken pieces, ensuring they are fully submerged. Cover the bowl and refrigerate for at least 4 hours, or preferably overnight.

In a shallow dish, combine the all-purpose flour, cornstarch, salt, paprika, garlic powder, onion powder, black pepper, and optional cayenne pepper. Whisk until everything is evenly distributed.

While the chicken marinates, prepare the sauce. In a small bowl, mix together the mayonnaise, sriracha, lime juice, and minced garlic. Stir until smooth, then cover and refrigerate until you're ready to assemble the sliders.

Pour the oil into a large, heavy-bottomed pot or Dutch oven to a depth of about 2 inches. Heat over medium-high heat until the oil reaches 350°F (175°C). Use a thermometer for accuracy.

Working with one piece at a time, remove the chicken from the buttermilk, letting any excess drip off. Dredge it thoroughly in the flour mixture, pressing the flour onto the chicken to create a thick coat. For an extra crispy crust, dip it back into the buttermilk and then into the flour a second time.

Carefully place a few pieces of chicken into the hot oil, being careful not to overcrowd the pot. Fry for 5-7 minutes, flipping halfway through, until the chicken is golden brown, crispy, and cooked through (internal temperature reaches 165°F).

Remove the cooked chicken from the oil and place it on a wire rack to drain. This helps it stay crispy. Lightly season with a pinch of salt while it's still hot. Repeat with the remaining chicken pieces.

Brush the cut sides of the slider buns with melted butter. Toast them in a skillet over medium heat or under the broiler for 1-2 minutes until lightly golden.

Spread a generous amount of spicy aioli on the top and bottom buns. Place a piece of crispy fried chicken on the bottom bun, top with a few pickle slices, and cover with the top bun. Serve immediately.