Prepare the chicken coating: In one shallow dish, mix the flour, cornstarch, salt, pepper, paprika, and garlic powder. In a second dish, place the beaten eggs mixed with the buttermilk.
Dredge the chicken pieces first in the flour mixture, shaking off excess. Dip completely into the egg/buttermilk mixture. Finally, press firmly back into the flour mixture to coat thoroughly.
Heat about 2 inches of vegetable oil in a deep skillet to 350°F (175°C).
Carefully place the coated chicken pieces into the hot oil, ensuring not to overcrowd the pan. Fry for 4 to 6 minutes, turning occasionally, until golden brown and cooked through (internal temperature of 165°F or 74°C).
Remove the chicken from the oil and place it on a wire rack lined with paper towels to drain excess oil.
Prepare the garlic sauce: In a small bowl, whisk together the mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper until smooth.
Lightly butter the cut sides of the slider buns. Toast them in a dry skillet or under the broiler until lightly golden.
Assemble the sliders: Place one piece of crispy chicken on the bottom half of each bun. Top generously with the prepared garlic sauce. Place the top bun on the chicken.
Serve immediately.
Notes
For extra crispiness, let the dredged chicken rest on a rack for 10 minutes before frying.
You can air fry the chicken at 400°F (200°C) for 12-15 minutes, flipping halfway, instead of deep frying.
Add a thin slice of pickle or a small leaf of lettuce to the slider before serving for texture contrast.